Scientific paper
Rhodium-Catalyzed Reactions of a Vinyldiazoacetate with .^-Substituted Semicyclic Enaminones
Andreas Müller, Andreas Endres and Gerhard Maas*
Institute for Organic Chemistry I, University of Ulm, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
* Corresponding author: E-mail: gerhard.maas@uni-ulm.de
Received: 08-09-2008
Dedicated to Professor Branko Stanovnik on the occasion of his 70"' birthday
Abstract
The rhodium-catalyzed reaction of dimethyl 3-diazo-1-propene-1,3-dicarboxylate (4) with ^-substituted five-membe-red semicyclic enaminones 1 yields (3-ammoniopropyl)cyclopentadienides 7 and/or dienamines 8 which formally represent products of carbenoid insertion into the enaminic ß-C-H bond of 1. The thermal isomerization 8 ^ 7 is facilitated by electron-donating substitutents at the N atom and at the carbonyl group of the enaminone moiety. Thus, ^-alkyl substituted dienamines 8 in general undergo the isomerization, while ^-phenyl substituted analogues do not rearrange. The isomerization behavior of the ^-methyl-3-(anthracen-9-ylcarbonyl)-substituted dienamine 8c is complex: isomerization into betaine 7c is achieved in low yield in the presence of sodium methanolate, while thermal impact in the presence of silica gel generates pentacycle 9 as a result of an intramolecular Diels-Alder reaction at the anthracene moiety. In complete analogy to the transformation 1 ^ 8, the rhodium-catalyzed reaction of vinyldiazoacetate 4 with the dime-done-derived 3-morpholinocyclohex-2-en-1-one 11 yields the olefinic C-H insertion product 12.
Keywords: Cyclopentadienides, diazo compounds, dienamines, enaminones, rhodium carbenoids
1. Introduction
Enaminocarbonyl compounds appear to be versatile substrates for transition-metal promoted carbenoid reactions of diazo compounds, because they offer three centers of enhanced electron density1 to the electrophilic metal carbene intermediates, namely the N- and ß-C atom of the enamine function as well as the carbonyl oxygen atom. Although the multiple reactivity of the N-C= C-C=O unit has found numerous applications in organic synthesis,2 it appears that the scope of carbenoid reactions with enaminocarbonyl compounds as substrates has not been fully exploited yet. Neverthelesss, the available results confirm that different reaction pathways are possible.
Kascheres and coworkers have studied the copper-catalyzed reactions of diazoketones and diazoacetates with primary and secondary enaminones and have observed products derived from initial insertion of the carbene moiety into the N-H or enaminic ß-C-H bond, depending on the structure and the substitution pattern of the enaminone.3'4 In contrast, we have found that copper-catalyzed alkoxycarbonylcarbene transfer to acyclic tertiary
Scheme 1. Carbenoid reactions of methyl diazoacetate or vinyldiazoacetate 4 with semicyclic enaminocarbonyl compounds.
(i.e. ^,^-disubstituted) enaminones and enamino esters yields 2-acyl-3-aminocyclopropane-1-carboxylates, which easily undergo ring-opening.5 With semicyclic enaminones 1 (Scheme 1), enamino esters 2 are obtained, which appear to be products of carbene insertion into the enaminic double bond.6 It is likely, however, that these products are also formed via initial cyclopropanation of the enamine double bond followed by spontaneous ring-opening. Notably, the copper-catalyzed reaction of dimethyl diazomalonate with acyclic tertiary enaminones provides dihydrofurans and C-2 substituted enaminones, both in modest yields.7 In this case, the metal-carbene intermediate does not cyclopropanate the enamine double bond but rather attacks the carbonyl oxygen (carbonyl ylide formation) and the nucleophilic ß-C atom of the enamine moiety.
Carbenoid reactions of vinyldiazoacetates have been investigated extensively by H. M. L. Davies and cowor-kers.8,9 Metal carbenes derived from these particular diazo compounds are considered to have a donor-acceptor substitution at the carbenic carbon atom, in contrast to the purely acceptor-substituted alkoxycarbonyl and bis(alkoxy-carbonyl)carbenoids.8 This electronic difference often gives rise to changes in reactivity, chemo- and stereoselecti-vity. We have reported earlier10 that the rhodium-catalyzed dediazoniation of vinyldiazoacetate 4 in the presence of ^-methyl-substituted five-, six-, and seven-membered semicyclic enaminones 3 yields (ra-ammonioalkyl)cyclo-pentadienides 5 (Scheme 1) in fair to excellent yields (R = Ph, 4-substituted phenyl, 2-thienyl, 2-furyl). Only in a few cases (e.g. n = 1, R = OMe, Ot-Bu), semicyclic dienami-nes 6 were obtained as competing products, but they could be isomerized thermally into betaines 5.
In this paper, we present new results on the carbe-noid reaction of vinyldiazoacetate 4 with five-membered semicyclic enaminones having substitution patterns diffe-
rent from those of 3. These results show the scope of the reaction for the preparation of betaines of type 5 and die-namines of type 6.
2. Results and Discussion
A slight excess of vinyldiazoacetate 4 was treated with a catalytic amount of dirhodium tetraacetate in the presence of a five-membered semicyclic enaminone 1. Dediazoniation of 4 proceeded smoothly at room temperature, and depending on the substitution pattern of 1, either a (3-ammoniopropyl)cyclopentadienide 7, or a semicyclic 1-dienamine 8, or both products were formed (Scheme 2 and Table 1). Rh2(OAc)4 was the catalyst of choice: both Rh2(CF3COO)4 (ether, r.t.) and copper(I) triflate (CH2Cl2, reflux) provided significantly lower product yields, while Cu(acac)2 was totally unef-fective.
Scheme 2. Carbenoid reactions of vinyldiazoacetate 4 with enaminones 1. For substituents and yields, see Table 1.
Table 1. Carbenoid reactions of vinyldiazoacetate 4 with enaminones 1; products and isolated yields.
1, 7, 8	R1	R2	Yield of	Yield of	Conversion
			betaine	dienamine	8 ^ 7
			7 [%]	8 [%]	
a	Me	1-adamantyl	52	0	
b	Me	2'-nitrobiphenylyl	37a	n.i.	6 h in boiling ethyl
		[C6Ht-4-(C6Ht-2-NO2)]			acetate/MeOH (5:1)
c	Me	anthracen-9-yl	0	28b	see text
d	i-Pr	2-thienyl	52	0	
e	ch2ch=ch2	2-thienyl	79a	c	5-6 h at 20 °C
f	CH2Ph	C6Ht-4-Cl	13	53b	200 °C/10 mind
g	CH2Ph	C6Ht-4-OMe	15	63b	200 °C/10 mind
h	CH2Ph	2-furyl	0	65b	200 °C/10 mind
i	Ph	C6Ht-4-Cl	0	74	not achieved
.i	Ph	2-thienyl	0	73	not achieved
a Yield obtained after complete isomerization 8 ^ 7; n.i. = not isolated. b Mixture of two diastereomers.
c Due to gradual isomerization 8 ^ 7 at r.t., a reliable yield of 8 cannot be given. d Isomerization 8 ^ 7 is accompanied by unspecific decomposition of 8.
The NMR data (^H: Exp. Part; 13C: Table 2) of betaines 7 are in good agreement with those reported earlier10 including the data of a related betaine the structure of which has been confirmed by X-ray diffraction analysis.11 According to the NMR spectra, dienamines 8e-h were obtained as a mixture of two diastereomers, while 8c,i^ were isomerically pure. C,H correlation spectra allowed a satisfactory spectral assignment in most cases. Based on the analysis of the chemical shift differences, we conclude that the pairs of diastereoisomers differ by the configuration at the enaminic double bond, but we made no efforts to assign the Z and E configuration. For the second double bond in the molecule (a,ß-unsaturated ester), we assume the Z configuration for general steric reasons. Furthermore, the observation of diastereotopic allylic CH2 protons for all dienamines, as well as diastereotopic allylic or benzylic NCH2 protons in the case of 8e-h, indicates axial chirality due to the non-planarity of the diene moiety and restricted rotation around the =C-C= single bond.
Scheme 3. Proposed pathway for the isomerization 8 ^ 7.
Table 2.13C NMR data (125.77 MHz, CDa3, 5 values) for betaines 7.
Com-	NCH2	NCH2-	NCH2-	CHcp	Other Ccp	OCH3	COOMe	Further Signals
pound		CH2	CH2CH2	cp	cp			
8a	47.8	25.4	24.4	121.6	110.7, 111.5, 125.6, 126.1	50.1, 50.5	167.56, 167.77	28.3, 32.9 (C-1ad), 36.6, 38.9, 50.3 (NMe), 221.2 (C=O)
8b	48.0	27.0	23.2	121.5	111.4, 115.0, 124.1, 126.9	49.0, 49.5	165.6, 166.1	32.3 (NMe), 123.8, 128.7, 129.0, 131.7, 132.9, 134.1, 138.5, 142.9, 148.8, 193.7 (C=O)
8ca	50.2	27.9	25.0	126.6	115.4, 119.6, 140.2, 140.6	49.5, 51.0	169.4, 169.8	33.2 (NMe), 126.1, 126.9, 127.7, 128.7, 129.3, 130.5, 132.6, 195.0
8d	43.3	24.9	23.1	124.8	113.6, 117.0, 123.9, 131.3	50.4, 50.6	167.4, 167.7	18.8 (CHMe2), 49.0 (CHMe2), 127.6, 133.5, 135.6, 148.2,2 186.7 (C=O) 2
8e	45.9	24.8	23.2	125.1	114.0, 117.1, 123.8, 127.7	50.3, 50.7	167.3, 167.8	49.0 (NCH2 allyl), 123.75 (=CH2), 131.5, 133.9, 135.9, 158.2, 186.9 (C=O)
8f	47.1	25.1	23.5	130.5	113.9, 116.9, 123.7, 125.0	50.3, 50.4	167.1, 167.3	51.2 (NCH2Ph), 127.8, 128.0, 128.7, 129.2, 131.0, 140.7, 194.4 (C=O)
8g	47.0	24.8	23.4	124.3	113.4, 116.6, 123.6, 131.9	50.2, 50.4, 50.8	167.23, 167.29	55.3 (NCH2Ph), 113.02, 113.06, 128.6, 129.6, 130.6, 134.9, 135.6, 162.3 (C^^OMe), 195.0 (C=O) ""
8h	47.1	24.6	23.6	125.2	114.9, 117.2, 122.4, 136.9	50.3, 50.7	166.3, 167.4	51.0 (NCH2Ph), 112.5, 119.3, 129.1, 129.4, 129.6, 130.4, 145.3, 155.2, 181.5 (C=O)
Most of the dienamines 8 can be rearranged thermally to form the isomeric betaines 7 (Table 1), as was already reported for two ^-methyl substituted analogues.10 The rate of isomerization obviously depends both on the ^-substituent and on the substituent R2 of the acyl moiety. The data suggest that the isomerization is facilitated by electron-donating substituents which enhance the electron density at the C=C bond of the enaminone moiety (e.g., N-alkyl substituents and the adamantyl group at C=O). This interpretation is in line with our mechanistic proposal10 according to which the rearrangement starts with a proton transfer from the allylic position (=CH-C^2-COOMe) to the electron-rich ß-position of the enamine double bond,
followed by a 1,5-cyclization of the formed betaine A and ring-chain transformation of spiro compound B (Scheme 3). The latter step requires a proton transfer from the cyclopentene ring to the pyrrolidine nitrogen atom and is surely facilitated by an electron-donating substituent R1. In agreement with these arguments, the two N-phenyl substituted dienamines 8i and 8j were found to be thermally stable even at 200 °C. On the other hand, the influence of aromatic substituents in the acyl moiety is not clear.
A particular behavior was found for anthracene-substituted dienamine 8c (Scheme 4) which could not be rearranged thermally into betaine 7c. A thermogravimetric analysis revealed that decomposition of 8c started around
a In methanol-d4.
200 °C. However, when 8c was heated in toluene in the presence of activated silica for 14 h, two products were formed in low yield. While one of the products remains unknown, the second one was identified as polycycle 9 (two isomers) by an X-ray diffraction analysis (Fig. 1). This compound likely arises from an allylic double bond shift in 8c, followed by an intramolecular Diels-Alder reaction at the anthracene system.12,13
We checked next the possibility of a base-assisted isomerization of dienamine 8c. Treatment with 0.1 equiv of NaOMe resulted only in a sluggish reaction which after some days gave a mixture of several unidentified products
Scheme 4. Conditions: a) toluene, 180 °C, 14 h, silica gel. b) Na-OMe (1 equiv), MeOH, 15 h, r.t.
Figure 1. Molecular structure of 9 in the solid state (ORTEP diagram). Thermal displacement ellipsoids are shown at the 20% level. Selected bond lengths (À): N-C24 1.323(4); C12-C24 1.374(3); C11-C12 1.440(3); C11-O1 1.240(2). Selected torsion angles (°): C13-C12-C24-N 12.3(4); O1-C11-C12-C24 -1.2(4); C12-C13-C20-O2 21.6(3); C2-C3-C22-O4 24.7(4).
including oligomers. The reaction with 1 equiv of NaOMe generated a complex mixture of products from which the expected betaine 7c and 2,3-dihydroindole 10 could be isolated in low yields. The constitution of 10 was firmly established by X-ray diffraction analysis (Fig. 2). The mode of formation of 10, which includes the loss of four hydrogen atoms, is not yet clear.
Figure 2. Molecular structure of 10 in the solid state (ORTEP diagram). Thermal displacement ellipsoids are shown at the 30% level. Selected bond lengths (À): N-C9 1.375(2); C4-C5 1.371(3); C5-C6 1.408(2); C6-C7 1.372(2); C7-C8 1.421(2); C8-C9 1.414(2); C8-C9 1.414(2).
Dienamines 8 can be considered as the formal insertion products of a vinylcarbene moiety into the enami-nic ß-C-H bond of semicyclic enaminones 1. The formation of 8 is likely to occur by an initial electrophilic attack of the metal carbenoid derived from vinyldiazoace-tate 4 at the electron-rich ß-position of the enamine double bond followed by a proton shift. We have performed a few experiments to explore the scope of this reactivity pattern. Thus, it was found that the rhodium-catalyzed reaction of vinyldiazoacetate 4 with the dimedone-deri-ved morpholinocyclohexenone 11, which is not of the same structural type as the semicyclic enaminones 1, occurs in a completely analogous manner and provides the formal carbene insertion product 12 in high yield (Scheme 5). Like dienamines 8, compound 12 has axial chira-lity due to restricted rotation about the single bond connecting the vinylcarbene moiety with the cyclohexenone ring, causing the CH2 protons of the cyclohexenone ring and in the allylic side chain to be diastereotopic. Compound 12 was found to be thermally stable up to 150 °C, with unspecific decomposition taking place at higher temperatures. It is interesting to note that an analogous C-H insertion at enaminone 11 occurs with the carbene generated thermally from 1,1,1-trifluoro-2-diazo-3-nitro-propane.14
Scheme 5. Carbenoid C-H insertion reaction of vinyldiazoacetate 4 with enaminone 11.
3. Conclusions
In this study, we have collected new results on the competitive formation of betaines 7 and dienamines 8 from the carbenoid reaction of semicyclic five-membered enaminones 1 and vinyldiazoacetate 4. Substituents which enhance the basicity of the ring nitrogen atom (e.g. R1 = iPr vs. Me, Me vs. CH2Ph) facilitate the direct formation of betaines during the reaction, as well as the thermal iso-merization 8 ^ 7. On the other hand, a phenyl substituent prevents the formation of a betaine. An effect of substi-tuent R2 in the acyl moiety of the enaminone 1 (or diena-mine 8) is also obvious, but a general explanation cannot be given.
Another aspect of our results comes from a comparison with carbenoid reactions between enaminones and dimethyl diazomalonate.7 With both types of diazo compounds, vinyldiazoacetates 4 and diazomalonates, carbenoid insertion into the enaminic ß-C-H bond is the "normal" pathway, no matter whether enaminones such as 1 and 11 or acyclic tertiary enaminones are used as substrates. However, while the copper-catalyzed reaction of the last mentioned enaminones and dimethyl diazomalonate also yields a product derived from carbenoid attack at the carbonyl oxygen of the enaminone, we did not observe comparable products in our experiments with vinyldia-zoacetate 4, although it is a vinylogous relative of the dia-zomalonates.
4. Experimental Section
4. 1. General Information
NMR spectra: Bruker AMX 500 (1H: 500.14 MHz; 13C: 125.77 MHz) and Bruker AC 200 (^H: 200.13 MHz; 13C: 50.32 MHz) spectrometers. Unless stated otherwise, all spectra were recorded with the former instrument in CDCl3 solutions. TMS was used as the internal standard; 8 values are reported in ppm (mc = centered multiplet). When necessary, 13C signal assignments were derived from C,H COSY, HSQC and gradient-selected HMBC spectra. IR spectra: Perkin-Elmer IR spectrophotometer 883; wavenumbers [cm-1] are given. Elemental analyses: Perkin Elmer EA 240. Mass spectra: Varian MAT 711 (FD spectra) and SSQ 7000 (EI spectra). Column chromatography was performed under hydrostatic pressure (silica
gel Si 60, Macherey-Nagel, 0.063-0.2 mm) and under medium-pressure conditions (Merck Lobar columns, Li-chroprep Si 60, particle size 40-63 pm, two columns (240 X 10 mm and 310 x 25 mm) connected; gradient pump Merck-Hitachi L6200).
4. 2. Materials
Solvents were dried according to standard methods and stored under an argon atmosphere. All reactions were carried out in rigorously dried glassware under an argon atmosphere.
Vinyldiazoacetate 410 and enaminocarbonyl compounds 1e15 and 1f-j6 were prepared by literature methods. The synthesis of 1a by Eschenmoser's sulfide contraction method16 is described below. Enaminones 1b-d were synthesized from lactam acetals by analogy to a literature method.17
(£)-1-(1-Adamantyl)-2-(1-methyltetrahydro-1ff-2-pyrrolylidene)-1-ethanone (1a). A solution of 1-meth-ylpyrrolidine-2-thione (1.07 g, 9.27 mmol) in anh. THF (7 mL) was gradually added to a solution of 1-adamantyl bromomethyl ketone18 (2.39 g, 9.27 mmol) in anh. THF (7 mL). A voluminous white solid started to form after a few minutes. More THF (7 mL) was added, the mixture was stirred overnight, and the solvent was replaced by acetoni-trile (60 mL). To the stirred white suspension was added triphenylphosphane (2.20 g, 8.39 mmol) and triethylami-ne (1.25 mL, 9.97 mmol). A yellow solution was formed within 30 min which was stirred for another 30 min. During partial evaporation of the solvent, the major part of the formed by-products (Ph3P=S and NEt3 X HBr) precipitated in solid form and was filtered off. The mother liquor was evaporated to dryness, and the residue was separated by column chromatography (silica gel, 50 g, ether as elu-ent). The product was obtained as the second fraction and recrystallized from diethyl ether. Yield: 0.523 g (22%), large clear crystals. Mp 103 °C. 1H NMR: 8 1.71 (mc, 6H, 3 X CH2-adamantyl), 1.85 (d, J 10.0 Hz, 6H, 3 x CH2-ad.), 1.94 (mc, 2H, NCH2CH2), 2.02 (mc, 3H, 2 x CH-ad.), 2.87 (s, 3H, NNMe), 3.22 (t, J 7.5 Hz, 2H[, =CCH2), 3.37 (t, J 7.0 Hz, 2H, NCH2), 5.18 (s, 1H, =CH). 13C NMR: 8 20.9 (NCH2CH2), 28.6 (3 X CHadamantyj), 33.2 (C-1 ad.), 33.4 (NMe), 36.9 (3 x CH2 ad.), 39.7 (C-2,8,9 ad.), 44.3 (=CCH2), 54.2 (NCH2), 84.2 (NC=CH), 166.6 (NC=), 202.2 (C=O). IR (KBr): v 1634, 1548, 1483, 1447, 1415, 1207, 1163, 1097 (all s) cm-1. Anal. Calcd for C17H25NO (259.39): C 78.72, H 9.71, N 5.40. Found C 78.55, H '9.68, N 5.39.
(£)-2-(1-Isopropyltetrahydro-1fl^-2-pyrrolylidene)-1-(2-thienyl)-1-ethanone (1d). Yellow crystals, mp 120 °C. 1H NMR: 8 1.21 (d, 6H, CHMe2), 1.92 (quin, 2H, NCH2CH2), 3.34 (t, 4H, NCH2, =CC;H2), 4.01 (sept, 1H, CHMe2), 5.63 (s, 1H, =CHCO), 7.01 (dd, 1H, J 5.0 and
3.7 Hz, 4-Hthie), 7.35 (dd, 1H, J 5.0 and 1.0 Hz), 7.52 (dd, 1H, J 3.7 a^^ 1.0 Hz). 13C NMR: 5 19.1 (CHMe2), 20.3 (NCH2CH2), 34.1 (=CCH2), 45.9 (NCH2), 46.1 (NNCHM-e2), 85.6 (=CHCO), 126.9, 127.2, 129.0, 149.4, 166.3 (]S[C=), 179.8 (C=O). Anal. Calcd for C13H17NOS (235.35): C 66.34, H 7.28, N 5.95. Found C 66.0^, 7.12, N 5.98.
Catalytic Decomposition of Dimethyl (£)-3-Diazo-1-propene-1,3-dicarboxylate (4) in the Presence of Ena-minones 1; General Procedure. A solution of 4 (1.2 equiv relative to the enaminone) in dichloromethane (5 mL) was added during 10-24 h with an infusion pump to a stirred solution of enaminone 1 (1.5-3.5 mmol) and Rh2(OAc)4 (3-4 mol %). Stirring was continued until evolution of nitrogen had ceased or until the IR absorption of the diazo group had disappeared (normally 1-2 h). In some cases, most of the betaine 7 crystallized from the mixture and was collected by filtration. An additional small portion of product was then obtained by column chroma-tography of the mother liquor (silica gel, elution with ethyl acetate). If the product did not crystallize from the reaction mixture, the solvent was removed at 20 °C/0.01 mbar, and the residue was fractionated by column chromato-graphy over silica gel. Elution with ethyl acetate furnished the following fractions: a) a small amount of unidentified products; b) a mixture of dienamine 8 (if formed) and catalyst which was separated by a second column chromato-graphy (Merck Lobar columns, silica gel, elution with ethyl acetate). Further elution with methanol yielded betaine 7, which was purified further by chromatography (Merck Lobar columns, silica gel, elution with ethyl acetate).
Reaction with Enaminone 1a; 3-[2-(1-Adamantyl)car-bonyl-3,5-di(methoxycarbonyl)cyclopentadienide] propyl(methyl)ammonium (7a): 478 mg (1.84 mmol) of 1a, 407 mg (2.21 mmol) of 4, 29 mg (0.067 mmol) of Rh2(OAc)4. Time for addition of 4: 100 h. Betaine 7a was isolated by column chromatography and recrystallized from ethyl acetate (395 mg, 52%). Slightly beige powder, mp 161 °C dec. 1H NMR: 5 1.64-1.80 (m, 6H, CH2 mantyi), 1.84 (mc, 6H, 3 x CH2 ad.), 1.95 (mc, 3H, 3 x (C:^ ad.), 2.04 (mc, 2H, NCH2CH2), 2.35-^.55 (m, 2H, CH2C=C), 2.53c (s, 3H, NMe2), 2.925 (mc, 2H, NCH2), 3.61 (s, 3H, OMe), 3.65 (s, 3H, OMe), 7.08 (s, 1H, ^CHcp), 8.26 (br s, 2H, N+H2). 13C NMR: Table 2. IR (KBr). v 3431 (m), 3100-2400 (broad bands), 1739 (m), 1678 (s), 1624 (vs), 1469 (vs), 1246 (vs), 1211 (s), 1192 (s), 1165 (vs), 1137 (s), 1083 (s) cm-1. Anal. Calcd for C24H33NO5 (415.53): C 69.37, H 8.00, N 3.37. Found C 68.36, H 7.84, N 3.10.
Reaction with Enaminone 1b: The product mixture was subjected to column chromatography (cc) over silica gel. On elution with ethyl acetate, betaine 7b and dienamine
8b were obtained in the same fraction. This fraction was submitted to cc again, this time using ethyl acetate/MeOH (5:1). This procedure gave pure 7b and a mixed fraction containing 7b and 8b. Complete isomerization of 8b to 7b was achieved by keeping the latter fraction at reflux for 6 h. The betaine precipitated as a yellow powder on concentrating the cold ethyl acetate solution (37% yield). Mp 177 °C dec. 1H NMR (DMSO-rfg): 5 1.94 (mc, 2H, NCH2CH2), 2.55 (s, 3H, NMe), 2.80-2.90 (m, 4H, NCH2 and N(CH2)2CH2), 3.03 (s, 3H, OMe), 3.60 (s, 3H, OMe), 6.91 (s, 1H, CHcp), 7.30-7.45 and 7.85-7.98 (2 x m, 8Haryl), 8.41 (br s, 2H, N+H2). 13C NMR: Table 2. IR (KBr). v 3440 (m), 3060-2300 (broad bands), 2503 (m), 1738 (w), 1644 (s), 1524 (s), 1491 (s), 1446 (s), 1244 (vs) cm-1. Anal. Calcd for C2gH2gN2O7 (478.50): C 65.26, H 5.48, N 5.85. Found C 64.^49, ^ ^.42, N 5.35.
Reaction with Enaminone 1c: After a total reaction time of 3 days, the solvent was evaporated, and the residue was stirred with ethyl acetate, yielding crude dienamine 8c as a solid. Recrystallization from hot ethyl acetate furnished yellow-beige crystals, mp 66 °C, in 28% yield. 1H NMR: 5 2.00-2.06 (m, 2H, NCH2CH2), 2.82 (s, 3H, NMe), 2.98 and 3.02 (AB part of ABX si)in system, 2H, =CHCH2), 3.22 (t, 2H, =CCH2), 3.52 (mc, 2H, NCH2), 3.72 (s, 3H, OMe), 3.91 (s, 3H, OMe), 7.1^2 (X part of ABX system, 1H, =CH), 7.30-7.45 and 7.85-7.98 (2 x m, 8Hanthryl), 8.39 (s, 1H, 10-Hanthryl). 13C NMR: 5 21.2 (C-4pyrr), 3^.2 (=CHCH2), 37.7 (NMe), 51.9 (C-3pyrr), 52.0 (OMe), 52.1 (OMe), 56.7 (NCH2), 105.5 (=CCOOMe), 124.8 (NC=C), 125.0 (C-10anthryl), 125.2, 127.0, 128.3, 132.2 (=CHCH2), 133.0, 135.2, h(57.2 (NC=C), 168.2 and 170.9 (COOMej), 193.3 (C=O). IR (KBr). v 1740 (s), 1714 (s), 1536 (vs), 1238 (s) cm-1. Anal. Calcd for C28H27NO5 (457.52): C 73.51, H 5.95, N 3.06. Found C 73.^6, ^ 6.02, N 3.00.
Reaction with Enaminone 1d: The reaction was carried out with 4 (469 mg, 2.55 mmol), 1d (500 mg, 2.12 mmol) and Rh2(OAc)4 (34 mg, 0.077 mmol, 3 mol %) according to the general procedure and gave only betaine 7d (430 mg, 52% yield). Viscous yellow oil. 1H NMR: 5 1.22 (d, J 6.5 Hz, 6H, CHMe2), 2.17 (mc, 2H, CH2), 2.86 (mc, 2H, CH2), 3.17 (mc, 2H, NCH2), ^3.24 (sept, J 6.5 Hz', 1H, CHMe2), 3.40 (s, 3H, OCH3), 3.72 (s, 3H, OCH3), 7.00 (dd, J 5 and 4 Hz, 1H, 4-Hthienyl), 7.29 (s, 1H, =CHcp), 7.41 (dd, J 4 and 1 Hz, 1H, Hthjen), 7.48 (dd, J 5 and 1Hz, 1H, Hthjenyl), 8.82 (br s, N+H2). 13C NMR: Table 2. IR (neat): v 3450-2300 (br, N+H2), 1721 (sh), 1645 (br, vs, C=O), 1484 (s), 1435 (vs), 1413 (vs), 1266 (vs), 1233 (vs) cm-1. Anal. Calcd for C2oH25NO5S (391.49): C 61.36, H 6.44, N 3.58. Found: C 61.5, H 6.4, N 3.3.
Reaction with Enaminone 1e: The reaction was carried out with 4 (443 mg, 2.41 mmol), 1e (500 mg, 2.01 mmol) and Rh2(OAc)4 (43 mg, 0.096 mmol, 4 mol %) and furnished betaine 7e and dienamine 8e in a combined yield of
741 mg (79%). Neat dienamine 8e rearranges to form 7e within a few hours at r.t.
Data for betaine 7e: Viscous yellow oil. 1H NMR: 5 2.12 (mc, 2H, NCH2CH2), 2.86 (mc, 2H, CH2-Cp), 3.02 (mc, 2H, NCH2), 3.39 (mc, 2H, NCH2 allyl), 3.40 (s, 3H, OC:H3), 3.69 (s, 3H, OCH3), 5.32-5.35 (m, 2H, CH=CH2), 5.73 (m3, 1H, CH=CH2), 7.00 (dd, J 4.9 and 3.9 Hz, 1H, 4-Hthieny3), 7.31 (s, 1H, CH3p), 7.41 (dd, 3J 3.9 Hz, |4J| 1.1 Hz, 1H, 3-Hthienyl), 7.50 (dd, 3J 5.0 Hz, |4J| 1.1 Hz, 1H, 5-Hthienyl), 9.09 (br s, 2H, N+H2). 13C NMR: Table 2. IR (fil^): V 3200-2200 (br, NH2+), 1732 (s), 1643 (vs), 1483 (s), 1442 (s), 1410 (s), 1266 (vs), 1236 (vs), 1195 (s) cm-1. Anal. Calcd for C20H23NO5S (389.47): C 61.68, H 5.95, N 3.60. Found: C 61.6, H 6.1, N 3.5.
Data for dienamine 8e: Viscous yellow oil, 2:1 mixture of diastereomers. In the following, data for the minor isomer are given in brackets. 1H NMR: 5 1.86-2.06 (m, 2H, 4-H2 pyrrolidine, both isomers), 2.55 [3.23] (m3, 3-H2 pyrr), 3.05-3.45 (several m, CH2COOMe, NCH2 ring, both isomers), 3.62-3.71 (4 x s, OMe, both isomers), 3.78-3.83 [4.05-4.16] (m, 2H, NCH2CH=), 5.10-5.25 (m, 2H, CH=CH2, both isomers), 5.62 [5.82] (mc, 1H, CH=CH2), 6.92 (br dd, J 4.3 Hz, 1H, 5-Htlienyl), 7.13 [7.02] (X part of ABX system, 1H, NCH(CH=), 7.30-7.38 (m, 2H, 3- and 4-Htlienyl, both isomers). 13C NMR: 5 21.8 [20.3] (C-4pyrr), 35.:( [^3.7] (CH(CO), 36.4 [45.7] (CH(), 51.9 (OCH3), 52.1 (OCH3), 53.6 [52.5] (NCH(CH), 53.9 [56.0] (C-5pyrr), 98.6 [^6.5] (NC=C), 118.9 [118.3]
(=CH(), 126.8 (C-4tlienyl), I29.7 (C-3tlienyl), I29.9 (C-
5tlienyl), 131.5 (CH), 134.4, 136.6 [137.4], 147.2 (C-2tlienyl), 165.0 (NC=), 167.4 [167.6] (C=O), 170.6 [168.2] (C=(yl), 184.1 [180.0] (C=O). IR (film): v 1736 (s), 1715 (s), 1667 (s), 1592 (s), 1511 (s), 1474 (m), 1436 (s), 1415 (s), 1353 (m), 1265 (vs) cm-1. Anal. Calcd for C(0H(3NO5S (389.47): C 61.68, H 5.95, N 3.60. Found: C 61.0, H 6.3, N 3.3.
Reaction with Enaminone 1f: The reaction was carried out with 4 (410 mg, 2.22 mmol), 1f (500 mg, 1.86 mmol) and Rl((OAc)4 (29 mg, 0.07 mmol, 3 mol %) and furnished betaine 7f (97 mg, 13% yield) and dienamine 8f (397 mg, 53% yield). Heating of 8f in a Kugelrohr apparatus at 200 °C for 10 min resulted in partial decomposition and formation of betaine 7f, which could be isolated after chromatography in 26% yield.
Data for betaine 7f: Yellow oil. 1H NMR: 5 2.17 (m3, 2H, NCH2CH2), 2.93 (mc, 4H, NCH2CH2CH2), 3.21 (s, 3Hc, OCH3), ^.56 (s, 3H, OCH3), 3.S.3 (s, 2H, NCH(Pl), 7.26-37.33 (m, 8H, CH and Ha3ryl), 7.62 (dd, 2H, Haryl),29.27 (br s, 2H, N+H(). 13C NMR: Tialb^e 2. IR (film): v 3400-2200 (br, N+H(), 1738 (sh), 1643 (vs), 1590 (s), 1544 (m), 1484 (s), 1443 (s), 1409 (s), 1350 (m), 1233 (vs), 1199 (s), 1170 (s) cm-1. MS (FD, 8 kV): m/z (%) 468 (90) [MH+], 467 (100) [M+, 35a], 435 (27) [M+ - CH3OH], 403 (10) [M+ - 2 CH3OH]. Anal. Calcd for C(gH(gClNO5 (467.95): C 66.74, H 5.60, N 2.99. Found: C 66.9, H 5.7, Nf 3.1.
Data for dienamine 8f: Yellow oil, 1.3:1 mixture of diastereomers. In the following, the data for the second isomer are given in brackets (in some cases, assignments may be interchanged). 1H NMR: 5 1.97-2.04 (m, 2H, 4-
H( py^^olidine), 3.14 [2.56] (m3, 2H, 3-H( py^^), 2.86 [2.92] (AB part of ABX system, |JAB| 20.4 Hz, JAX = JBX = 7.2 Hz, 2H, CH2CO), 3.35 [3.7A3B] (mc, 2H, 5A-XH2 pyBrrX), 4.42 [4.64] (AB system, |(J| 16.0 [16.^] Hz, 2H, ^^C:H(Pl), 3.54, 3.59 [3.65, 3.66] (4 x s, 3H, COOMe), 6.87 [6.79] (X part of ABX system, 3JAX = 3JBX = 7.2 Hz, 1H, =CHCH(), 7.06-7.39 (m3, 9H, HAr). X3C NMR: 5 22.4 [21.8] (C-4pyrr), 35.5, 36.7 [35.1, 35.7] (CH(), 51.2, 52.0, 52.2 (4 x COOMe), 52.1 [54.4] (NCH(Pl), 54.2 [57.0] (C-5pyrr), 99.0 [97.0] (NC=C), 127.2, 127.6, 127.7, 127.8, 128.3, 128.7, 128.5, 129.1, 129.4 (all CAr), 134.4, 135.6, 135.9, 136.3 [137.0] (=CHCH() 141.3 [140.6] (C-Cl), 156.5 (NC=C), 167.2, 167.4, 167.9, 170.4 (all COOMe), 193.2 [188.1] (C=O). IR (film): v 1737 (s), 1712 (s), 1668 (m), 1612 (s), 1589 (s), 1566 (m), 1518 (s), 1434 (s), 1265 (vs), 1199 (m), 1171 (m), 1088 (m) cm-1. MS (FD, 8 kV): m/z (%) 467 (100) [M+, 35Cl]. Anal. Calcd for C(gH(gCl-NO5 (467.95): C 66.74, H 5.60, N 2.99. Found: C 66.7, H 5.6, N 3.4.
Reaction with Enaminone 1g: The reaction was carried out with 4 (359 mg, 1.95 mmol), 1g (500 mg, 1.62 mmol) and Rh2(OAc)4 (34 mg, 0.08 mmol, 4 mol %) and furnished betaine 7g (113 mg, 15% yield) and dienamine 8g (473 mg, 63% yield). Heating of 8g in a Kugelrohr apparatus at 200 °C for 10 min resulted in both unspecific decomposition and formation of betaine 7g which could be isolated after chromatography in 27% yield.
Data for betaine 7g: Yellow oil. 1H NMR: 5 2.15 (mc, 2H, NCH2CH2), 2.85 (mc, 2H, NCH2CH2), 2.95 (mc,
2Hc, CH2-Cp),23.232 (s, 3H, OcCH3), 3.812 (s, 23H, OCH3)c,
3.83 (NCH2Ph), 3.89 (s, 3H, OCH3), 6.84-7.68 (m, 9H, Haryl), 7.31 (s, 1H, CH3p), 9.39 (br s, 2H, N+H(). 13C NMR: T;all^e 2. MS (FD, 8 k,,/): m/z = 463 (100) [M+], 431 (29) [M+ - CH3OH), 399 (8) (M+ - 2 CH3OH). Anal. Calcd for C(7H(9NOg (463.53): C 69.96, H 6.30, N 3.02. Found: C 69.7, H 6.4, N 3.0.
Data for dienamine 8g: Yellow oil, 1.2:1 mixture of diastereomers. 1H NMR, signal assignments to one or the other isomer are not made: 5 1.94 [1.94] (m3, 2H, NCH(CH(), 2.55 (m3, 1H, NCH), 2.80-3.10 (severail m, 4 H), 3.32 (m3, 1H), 3.54, 3.60, 3.66, 3.67, 3.77, 3.79 (all s, 3H, OMe of both isomers), 4.39 [4.58] [m3, AB part of ABX system, |(J| 18.0 Hz, 2H, NCH(Pl), 63.69-7.47 (m, 10H, Haryl and CH(CH=). 13C NMR, signals assignments to one or the other isomer are not made: 5 20.4 and 22.0 (C-4pyrr); 35.0, 35.2, 35.4 and 36.5 (C-3pyrr and CH(COOMe); 50.2, 51.8, 55.1 (3 x OCH3); 54.2 (NCH( ring), 53.9 and 56.9 (NCH(Pl), 97.5 and 99.8 (NC=C); ^^7.1, 127.3, 127.5, 128.4, 128.6, 128.8, 129.0, 129.89, 129.92, 134.6, 134.8, 135.2, 135.6, 135.8; 136.3 [136.5] (=CHCH(); 161.0 (CarylOMe), 164.5 [166.0] (NC=C),
189.3 [194.1] (C=O). IR (film): v 1643 (br, s), 1603 (s), 1484 (s), 1442 (s), 1265 (vs), 1169 (s) cm-1. Anal. Calcd for C27H29NO6 (463.53): C 69.96, H 6.30, N 3.02. Found: C 69.9, H 6.3, N 3.4.
Reaction with Enaminone 1h: The reaction was carried out with 4 (413 mg, 2.25 mmol), 1h (500 mg, 1.87 mmol) and Rh2(OAc)4 (40 mg, 0.09 mmol, 4 mol %) and furnished dienamine 8h (512 mg, 65% yield). Heating of 8h in a Kugelrohr apparatus at 200 °C for 10 min resulted in both unspecific decomposition and formation of betaine 7h, which could be isolated after chromatography in 28% yield.
Data for betaine 7h: Yellow oil. 1H NMR: 5 2.20 (mc, 2H, NCH2CH2), 2.80-3.00 (m, 4H, NCH2CH2CH2), 3.50 (s, 3H, OM4e), 3.67 (s, 3H, OMe), 3.79 (psejudo-t, 2H, NCH2Ph), 6.49 (dd, J 3.5 and 1.5 Hz, 1H, Hfuryl), 6.86 (d, J 3.5 Hz, 1H, Hfuryl), 7.50 (dd, J 1.5 and 0.5 H;u, 1H, Hfuryl). 13C NMR: Table 2. IR (film): v 3400-2300 (br, N+-H[-,), 1738 (sh), 1668 (s), 1573 (s), 1530 (s), 1473 (s), 1442 (s), 1411 (s), 1392 (s), 1265 (s), 1235 (s), 1146 (s), 1105 (m) cm-1. MS (FD, 8 kV): m/z (%) 423 (100) [M+], 391(7) [M+ - CH3OH)]. Anal. Calcd for CS4HS5NOg (423.46): C 68.07, H 5.95, N 3.31. Found: C 68.1, H 6.2, N 3.4.
Data for dienamine 8h: Yelllow oil, 2:1 mixture of diastereomers. In the following, data for the minor isomer are given in brackets. 1H NMR: 5 1.90-2.04 (m, 2H, NCHsCHs, both isomers), 2.98 [2.55] ("t", 2H, CHsCH=), 3.26 [3.26] (mc, 2H, 3-Hs pyrr), 3.54 and 3.59 [3.66, 3.70] (s, 3H, OCH3), Č3.6 (mc, ]S^C]Hs, both isomers), 4.40 [4.60] (AB system, |sJ| 16.0° [15.7] Hz, 2H, NCHsPh), 6.33 [6.30] (br s, 1H, 4-Hfuryl), 6.81 [6.65] (br s, 1H, 3-Hfuryl), 7.06 (d, 2H, Haryl), 7.18-7.31 (m, 3H, Haryl), 7.25 [7.01] (br s, 1H, =CHCHs), 7.36 [7.35] (br s, 1H, 5-Hfuryj). 13C NMR: 5 21.8 [20.3] (C-4pyrr), 36.2 [34.9] (C-3pyrr), 35.0 [35.6] (CHsCO), 52.1, 52.3 (2 x OCH3, both isomers), 54.3 (C-5pyrr), 54.5 (NCHsPh), 97.9 (NC=C), 111.0 (C-4f,r„,), 114.^ (C-3f,r„,), 127.2, 127.5, 128.4, 128.7, 133.7
aryl
) 136.0 (=CHCHs), 137.0 (=CCOOCH3), 143.8 2
l), 154.6 (C-2furyl), 156.3 (NC=C) 167.7, 170.9,
(all C (C-5f
179.9 (3 x C=O). IR (film): v 1737 (s), 1713 (s), 1609 (s), 1518 (s), 1469 (s), 1436 (s), 1265 (vs) cm-1. MS (EI, 70e-V): m/z 423 (31) [M+], 392 (4) [M+ - CH3OH], 364 (4), 350 (100) [M+ - CHsCOOCH3], 328 (31) [M+ -CH2COOCH3 - CH3OH2]. Anal. 3Calcd for C24H25NO6 (423.46): C 68.07, H 5.95, N 3.31. Found: C 68.0, H 6.4, N 3.1.
Reaction with Enaminone 1i: The reaction was carried out with 4 (186 mg, 1.0 mmol), 1i (250 mg, 0.83 mmol) and Rhs(OAc)4 (13.3 mg, 3 mol %) and furnished dimethyl 5-(4-chlorophenyl)-5-oxo-4-(1-phenyltetrahydro-1H-pyrrol-2-ylidene)pent-2(Z)-ene-1,3-dicarboxylate (8j) as a colorless oil (278 mg, 74% yield). The NMR spectra showed the presence of a single diastereoisomer. 1H NMR: 5 2.12 (mc, 2H, NCHsCHs), 2.91 (AB part of ABX
system, |sJAB| 18.0 Hz, 3JAX = 3JBX = 6.9 Hz, 2H, CHCHsC=0), 3.22 (mc, 2H, ^CCHs), 3.46 (s, 3H, OCH3), 3.66 (s, 3H, OCH3), 3.79 (mc, 1H, NCH), 3.87 (mc, 1H, NCH), 6.31 (t, X part of A^X system, 1H, =CHCHs), 6.88-7.18 (m, 5H, C^H^), 7.22 and 7.43 (AA'BB', 4H, CgH4Cl). 13C NMR: 5 ^2.0 (C-4pyrr), 35.6 (=CCHs und CHsC=0), 51.7 (OCH3), 52.0 (OCH3), 56.8 (NCHs), 102.1 (NC=C), 124.6, 126.2, 127.9, 129.2, 129.5 (all Caryj), 136.1 (CCl), 155.6 (i-Caryj), 163.7, 166.3 (COOCH3), 170.3 (COOCH3), 193.9 (C=O). IR (film): v 1719 (s), 1599 (s), 1589 (s), 1492 (s), 1435 (s), 1263 (vs), 1090 (vs), 1044 (s), 1013 (s), 909 (vs) cm-1. MS (FD, 8 kV): m/z 453 (100%) [M+]. Anal. Calcd for CS5HS4ClN05 (453.92): C 66.15, H 5.33, N 3.09. Found: C 66.^, H 5.4, N 3.4.
Reaction with Enaminone 1j: The reaction was carried out with 4 (410 mg, 2.22 mmol), 1j (500 mg, 1.86 mmol) and Rhs(0Ac)4 (29 mg, 0.07 mmol, 3 mol %) and furnished dimethyl 5-(2-thienyl)-5-oxo-4-(1-phenyltetrahydro-1H-pyrrol-2-ylidene)pent-2-ene-1,3-dicarboxylate (8i) as a yellow oil (577 mg, 73% yield). The NMR spectra showed the presence of a single diastereoisomer. 1H NMR: 5 2.08-2.17 (m, 2H, NCHsCHs), 2.98/3.02 (AB part of ABX system, 3JAX = 3JBX = 7.7 Hz, |sJAB| 18.2 Hz, 2H, CHsC0), 3.34 2H, C=CCHs), 3.66 (s, 3H, OCH3), 3.72 and 3.92 (mc, 2H, NCH2), 3.84 (s, 3H, OCH3), 6.48 (X part of ABX sycstem, 1H, =CHCHs), 6.90 (dd, J 5.9 and 3.8 Hz, 1H, 4-Hthienyl), 7.00 (d, J 8.2 Hz, 2H), 7.09 (t, J 7.4 Hz, 1H), 7.19 (t, Hz, 2H), 7.34 (dd, J = 3.8 and 1.1 Hz,
1H, 3-Hthienyl), 7.36 (dd, J =5.5 and 1.1 Hz, 1H, 5-Hthienyl).
13C NMR: 5 22.1 (C-4pyrr), 35.3 (CHsC0), 35.4 (C-3pyrr), 51.7 (0CH3), 51.9 (OCir[3) 56.8 (NCHs), 102.0 (NC^CT),
124.2, 126.1, 126.7 (C-4thienyl), 128.9, 130.4 (C-3thienyl), 130.5 (C-5thienyl), 133.6, 135.6, 142.7, 147.0 (C-2thienyl),
163.4 (NC=C), 166.5, 170.5, 185.1 (3 x C=0). IR (film): v 1737 (s), 1718 (s), 1658 (m), 1601 (s), 1510 (s), 1491 (s), 1475 (m), 1453 (m), 1435 (m), 1413 (m), 1353 (m), 1319 (m), 1275 (m), 1200 (m), 1169 (m), 1077 (m) cm1. MS (EI, 70 eV): m/z (%) 425 (21) [M+], 394 (3) [M+ -0CH3], 366 (3) [M+ - C00CH3], 352 (100) [M+ -CHsC:00CH3), 111(19) [C0C4H3S]. Anal. Calcd for CS3^S3N05S (425.50): C 64.92, H 5.45, N 3.29. Found: C 6^.0, ^ 5.^, N 3.4.
Synthesis of Polycycle 9: Dienamine 8c (99 mg, 0.22 mmol), activated silica gel (ca. 10 mg), and anhydrous toluene (3 mL) were placed in a thick-walled Schlenk tube, and the mixture was heated at 180 °C for 14 h. After cooling, the solvent was evaporated and the residue was submitted to column chromatography over silica gel. Elution with ethyl acetate gave two distinct fractions. The first one furnished an orange-red solid (3 mg) which was discarded. The section (green) fraction was concentrated and kept at -20 °C for 3 days. Compound 9 was obtained as a colorless solid (15 mg, 15% yield), mp 211 °C. 1H NMR
data indicate the presence of two isomers, but only the data of the major isomer are given here: 8 2.04 and 2.11 (2 x m[, 2H, NCH2CH2), 2.60 (dd, J 10.3 and 6.1 Hz, 1H), 2.78 (s 3H, NCH3), 2.857 (d, J 5.9 Hz, 1H), 3.18 (d, J 10.5 Hz, 1H), 3.34 (m[, J1 = J2 = 8.5 Hz, 2H, CH2C=), 3.47 (t, J 10.0 Hz, 2H, NCH2), ^.57 (s, 3H, OMe), 3.61 (s, 3H, OMe), 4.70 (s, 1H), 7.02-7.96 (8Harom). 13C NMR: 8 20.8 (C-4pyrr), 33.7 (C-3pyrr), 35.1 (NMee), 41.0, 48.0, 49.1, 50.0, 51.^ and 51.9 (CCOOMe), 58.5, 98.7, 121.7-126.3 (8 signals), 138.4, 139.1, 140.2, 143.5, 165.2 (C-2pyrr), 195.7 (C=O). IR (KBr). v 1742 (s), 1649 (m), 1553 (s) cm-1.
Synthesis of Betaine 7c and Dimethyl 7-(9-anthrylcar-bonyl)-2,3-dihydro-1-methyl-1H-indole-4,6-dicar-boxylate (10): A solution of NaOCH3 in methanol, prepared from sodium (4.2 mg, 0.18 mmol) and anhydrous methanol (5 mL), was added to an ice-cooled solution of die-namine 8c (84 mg, 0.18 mmol) in anh. methanol (15 mL). The mixture was allowed to react for 15 h, giving rise to at least six products as indicated by TLC. After neutralization of the orange-colored solution with aqueous NH4Cl, dihydroindole 10 separated as an orange solid within 10 min (11 mg, 13% yield). The mother liquor was chroma-tographed over silica gel. Elution with ethyl acetate furnished betaine 7c as the slowest moving fraction: 8 mg (10% yield) of an ochre powder, mp 207 °C dec.
Data for 7c: 1H NMR (CD3OD): 8 2.05 (br, 2H, Cp-CH2), 2.34 (br, 2H, NCH2CH32), 2.61 (s, 3H, NMe), 2.88 (br, 2H, NCH2), 3.37 (s, 3H, OMe), 3.79 (s, 3H, OMe), 7.14 (s, 1H, CH[p), 7.35-7.46 (m, 4H), 7.93 (d, J 8.6 Hz, 2H), 8.00 (d, J ^.4 Hz, 2H), 8.45 (s, 1H). 13C NMR: Table 2. IR (KBr). v 3447 (br. m), 1738 (w), 1686 (s), 1656 (s) 1535 (s), 1490 (s), 1443 (s), 1232 (vs) cm-1. Anal. Calcd for C28H27NO5 (457.52): C 73.51, H 5.95, N 3.06. Found C 72.89, H 5.93, N 3.14.
Data for 10: 1H NMR: 8 2.65 (s, 3H, COOMe), 2.78 (s, 3H, NMe), 3.51 (NCH2CH2), 3.80 (t, 2H, NCH2), 3.88 (s, 3H, COOMe), 7.26 (s, 1H), 7.45 (m[, 4H), 8.01 (d, J 5.5 Hz, 2H), 8.30 (d, J 6.0 Hz, 2H), 8.59 (s, 1H). 13C NMR: 8 28.8 (C-3), 39.9 (NMe), 51.6/52.0 (COOMe), 56.8 (C-2), 118.3 (C-5), 122.8 (C-6), 125.2, 125.3 (C-4), 127.7, 125.8, 126.7, 128.1, 130.6, 131.1, 132.5, 132.7, 140.5 (C-3a), 152.4 (C-7a), 166.1/168.4 (COOMe), 195.1 (C=O). IR (KBr): v 1726 (vs), 1644 (m), 1567 (m), 1299 (s), 1241 (vs), 1091 (s) cm-1. MS (EI, 70 eV): m/z (%) 453 (100) [M+], 421 (71).
Dimethyl 2-(4,4-dimethyl-2-morpholino-6-oxocyclohe-xen-1-en-1-yl)-1-propene-1,3-dicarboxylate (12): The
reaction was carried out with 4 (527 mg, 2.86 mmol), 5,5-dimethyl-3-morpholinocyclohex-2-en-1-one (11) (500 mg, 2.38 mmol), and Rh2(OAc)4 (38 mg, 3 mol %) according to the general procedure. Crystallization from ether at -10 °C yielded slightly beige crystals, mp 110 °C. Yield: 747 mg (86%). 1H NMR: 8 1.11 (s, 3H, CH3), 1.14 (s, 3H, CH3), 2.23 and 2.31 (AB system, |2J| 16.0 Hz, 2H,
CH2C=O, ring), 2.34 and 2.47 (AB system, |2J| 16.0 Hz, 2H, CH2, ring), 2.91 and 3.09 (AB part of ABX system, |2Jab| 18.0 Hz, 3Jax = 3Jbx = 6.0 Hz, 2H, =CHCH2CO), 3.21/3.23 (2 x t, J4.8 Hz, ^H, NCHAHB), 3.32/3.43 (2 x t, J 4.8 Hz, 2H, NCHaHb), 3.70 (s, 3H, OCH3), 3.73 (s, 3H, OCH3), 4.75 (t, J 4.8 Hz, 4H, O(CH2)2), 63.97 (X part of ABX system, 1H, =CHCH2). 13C NMR: 8 28.2 (CH3), 28.7 (CH3), 31.8 (C(CH3)2), 35.4 (CH2COOCH3), 42.9 (CH2), 49.2 (N(CH2)2), 49.9 (CH2C=O, ring), 51.9 (OCH3), 52.0 (OCH3), 66.9 (O(CH2)2), 108.3 (NC=C), 133.1 (C=CCOOCH3), 134.0 (CH^C:COOCH3), 163.0 (NC=C), 167.5, 176.7, 194.9 (3 x C=O). IR (KBr): v 1733, 1715, 1702, 1628 (C=O) cm1. Anal. Calcd for C19H27NO6 (365.42): C 62.45, H 7.45, N 3.83. Found: C 6^.3, ^ 7A, N 4.0.
X-ray Crystal Structure Detemination for 9 and 10.
Single crystals were obtained by evaporation of a solution in ethyl acetate in both cases. Data collection was performed at 293(2) K on an image-plate diffractometer (Stoe IPDS) using monochromated Mo-^a radiation (À = 0.71073 À). Both structures were solved by direct methods and refined (F2 values) using a full-matrix least-squares method. Hydrogen atom positions were calculated geometrically and treated as riding on their bond neighbors in the refinement procedure. Software for struc-
Table 1. Summary of crystallographic data and structure refinement details for compounds 9 and 10.
	9	10
Formula	C28H27NO5	C28H23NO5
Mr	457.51	453.47
Cryst. size, mm3	0.46 x 0.38 x 0.26	0.46 x 0.35 x 0.23
Crystal system	orthorhombic	monoclinic
Space group, Z	P 2l2l2l, 4	P 21/n, 4
a, À	9.5743(9)	13.257(3)
b, À	12.9563(8)	9.051(2)
c, À	19.8049(13)	19.386(5)
a, deg	90	90
ß, deg	90	104.55(3)
Y, deg V, À3	90	90
	2456.7(3)	2251.5 (9)
öcalcd, g cm-3	1.237	1.338
^(MoKg), mm-1	0.085	0.092
F(000), e	968	952
hkl range	±11, ±15, -23^24	±16, ±11, ±23
ß ß o min max'	2.06, 25.98	2.14, 25.92
Refl. measured	19515	18750
Refl. unique (Rint)	4740 (0.0545)	4357 (0.0750)
Param. refined	310	310
R(F)/wR(F2)		
(all reflections)a	0.0839 / 0.0926	0.0886 / 0.1186
Goodness of fit (GoF)b	0.841	0.644
^Pfin (max/min), e À-3	0.17/-0.16	0.15/-0.16
a R(F) = Z | | Fo | - | Fc | / Z |F„| ; wR(F2) = [Z(w(F„2 - Fc2)2) / Zw(F„2)2]1/2.
'GoF = [Zw(|F„|- |F|c)2/ (W„bs-Wpa,a„)]
1/2
ture solution and refinement: SHELX-97 [19]; molecule plots: ORTEP-3 [20]. Further details are provided in Table 3. CCDC-697829 (9) and -697830 (10) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via .
5. Acknowledgement
Financial support by the Fonds der Chemischen Industrie is gratefully acknowledged.
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Povzetek
Z rodijem katalizirane reakcije dimetil (-diazo-1-propen-1,(-dikarboksilata (4) z N-substituiranim petclenskimi semici-klicnimi enaminoni 7 vodijo do ((-amoniopropil)ciklopentadienov 8 in/ali dienaminov 9, ki formalno predstavljajo vri-njanje karbenoida v enaminsko C-H vez. Termično izomerizacijo olajšujejo elektrondonorski substituenti na dušiku in na karbonilni skupini enaminona. Na splošno N-alkil substituirani dienamini 9 izomerizirajo, medtem ko izomerizacija ne poteče pri N-fenil substituiranih spojinah 9. Izomerizacijske lastnosti N-metil-(-(antracen-9-ilkarbonil) substituira-nega dienamina 9c so kompleksne; z natrijevim metoksidom poteče izomerizacija do betaina, medtem ko pod termičnimi pogoji v prisotnosti silikagela nastane pentacikel 10, kot produkt intramolekularne Diels-Alderjeve reakcije na antra-censkem preostanku. Rodij-katalizirana reakcija vinildiazoacetata 4 s (-molfolinocikloheks-(-en-1-onom 12 pa je analogna s pretvorbo enaminona 7 v dienamin 9.