Organometallics 1995,14, 5533-5536
5533
Synthesis of a Novel Cyclic Germanium Enamine from Germylene and 2-Vinylpyridine and Its Stereoselective Aldol Type Reaction with Aldehydes Satoru Iwata, Shin-ichiro Shoda, and Shiro Kobayashi* Department of Molecular Chemistry and Engineering, Faculty of Engineering, Tohoku University, Aoba, Sendai 980, Japan Received July 21, 199P
A novel cyclic germanium(IV) enamine 3 has been prepared by the reaction of a germylene, bis[bis(trimethylsilyl)aminatolgermanium(II) (l),and 2-vinylpyridine (2). The aldol type reaction of the resulting enamine with various aldehydes 4 gave condensation products of 4,5-disubstituted l-oxa-2-germacyclopentane derivatives 5. The reaction proceeds in a stereoselective manner to give trans products when aliphatic aldehydes were used as electrophiles. In the case of using aromatic aldehydes, cis isomers predominate. The preferential formation of a cis or trans isomer was explained by assuming a n acyclic transition state for the aldol type reaction.
Introduction Enamines have greatly contributed to the progress of synthetic organic chemistry because of their high reactivity toward various e1ectrophiles.l Especially, lithoenamines have most frequently been utilized as nucleophiles in cross aldol reactions, alkylations, and asymmetric syntheses.2 In recent years, the development of a C-C bond-forming reaction which proceeds via a novel organometallicintermediate having a central metal of higher atomic number is of growing interest in organic synthesis. Much attention has been paid to the structure and reactivity of organogermanium species as reactive intermediates. Although there are several reports on germanium enolate formation and their r e a ~ t i v i t i e s , ~little - ~ is known about the synthesis and reactivity of germanium enamines. Normally, a germanium enamine is obtained only as the tautomer of an N-germylimine prepared by the reaction of tetravalent halogermanes and iminolithium derivatives;6there has been no report of the preparation of a germanium enamine starting from a divalent germanium compound (germylene). Recently, in the course of our investigations on the development of new polymerizations using germylene @
Abstract published in Advance ACS Abstracts, November 1, 1995.
(1)(a) Dyke, S. F. The Chemistry ofEnamine; Cambridge University
Press: Cambridge, U.K., 1973. (b) Reiff, H. Newer Methods of Preparative Organic Chemistry; Foerst, W., Ed.; Academic Press: New York, 1971;Vol. 6,p 48. (c) Wittig, G.;Hesse, A. Org. Synth. 1970, 50,66. (2)(a) Stork, G.;Terrell, R.; Szmuszkovisz, J. J . Am. Chem. SOC. 1954,76, 2029. (b) Meyers, A. I.; Williams, D. R.; Druelinger, M. J . Am. Chem. Soc. 1976,98,3072.(c) Meyers, A.I. Acc. Chem. Res. 1978, 11, 375. (3) (a)Lutsenko, I. F.; Baukov, Y. I.; Belavin, I. Y.; Tvorogov, A. N. J . Organomet. Chem. 1968,14, 229. (b) Michel, E.;Neumann, W. P. Tetrahedron Lett. 1986,27, 2455. (c) Inoue, S.;Sato, Y. Organometallics 1987,6 , 2568. (d) Yamamoto, Y.; Hatsuya, S.; Yamada, J. J . Chem. SOC.,Chem. Commun. 1988,1639. (4)Kobayashi, S.;Iwata, S.; Shoda, S. Chem. Express 1989,4 , 41. (5)(a) Kobayashi, S.; Iwata, S.; Yajima, K.; Shoda, S. J . Am. Chem. SOC.1992,114,4929. (b) Kobayashi, S.;Shoda, S. Adv. Mater. 1993, 5,57. (6) (a) Chan, L. H.; Rochow, E. G. J . Organomet. Chem. 1967,9, 231. (b) Lappert, M. F.; Palmer, D. E. J . Chem. SOC.,Dalton Trans. 1973,157.(c) Keable, J.;Othen, D. G.; Wade, K. J . Chem. SOC.,Dalton Trans. 1976,1.
s ~ e c i e s we , ~ found that a stable germylene, bis[bis(~rimethylsilyl)aminatolgermanium~II),8~ undergoes a rapid addition reaction to various a,/?-unsaturated carbonyl compounds with s-cis conformation t o give the corresponding cyclic germanium en01ate.~We have also demonstrated the synthesis of a poly(germanium enolate) by using a cyclic a,/?-unsaturated ketone with s-trans c~nformation.~ Here, we report synthesis of a novel bicyclic germanium(IV) enamine 3 by the reaction of the germylene 1 and 2-vinylpyridine (2). The aldol type reaction of the resulting enamine with various aldehydes 4 gives rise to 4,5-disubstituted l-oxa-germacyclopentane derivatives 5.9
Results and Discussion Synthesis of Germanium Enamine 3. The addition reaction of the germylene 1 to 2-vinylpyridine (2) occurred instantaneously at room temperature to afford the corresponding germanium(IV) enamine 3 in 95% yield (Scheme 1). The resulting enamine has a novel bicyclic structure fused by a l-aza-2-cyclogermapent-4ene ring (five-membered)and a l-azacyclohexa-3,5-diene ring (six-membered). The reaction was carried out in benzene& in an NMR sample tube, and the formation of the enamine was directly confirmed by IH NMR spectroscopy. The lH NMR spectrum of the resulting enamine showed a signal at 6 4.33 ppm ascribable t o the olefinic proton in (five-membered)moithe l-aza-2-cyclogermapent-4-ene ety. The peak at 6 1.84 ppm can be assigned to the methylene protons adjacent to the germanium atom. The signals at 6 0.36 and 4.3-7.1 are due to the protons (7) (a) Kobayashi, S.; Iwata, S.; Abe, M.; Shoda, S. J . Am. Chem. SOC.1990,112,1625.(b) Kobayashi, S.;Cao, S. Chem. Lett. 1993,25.
(c) Kobayashi, S.;Cao, S. Chem. Lett. 1993,1385. (d) Kobayashi, S.; Iwata, S.; Hiraishi, M. J . Am. Chem. SOC.1994, 116, 6047. (e) Kobayashi, S.;Iwata, S.; Abe, M.; Shoda, S. J . Am. Chem. SOC.1995, 117, 2187. (8)(a) Harris, D.H.; Lappert, M. F. J . Chem. SOC.,Chem. Commun. 1974,895.(b) Gynane, M.J. S.; Harris, D. H.; Lappert, M. F.; Power, P. P.; Riviere, P.; Riviere-Baudet, M. J . Chem. SOC.,Dalton Trans. 1977,2004. (9)The present study was previously presented in p a r t Kobayashi, S.; Shoda, S.; Iwata, S. Annu. Meet. Chem. SOC.Jpn. Prepr. 1991,61, 1818.
Q276-7333l95/2314-5533$Q9.QQlQ 0 1995 American Chemical Society
5534 Organometallics, Vol. 14, No. 12, 1995
Zwata et al.
Table 2. NMR Parameters and NOE for the Cis or Trane Isomer of Aldol Product 5 I3C NMR chem shift aldol NOE (%) at product irradiated H H' H3 H4 J(H3-H4) of GeCHz(ppm) 5a cis
trans
H3 H4 H3
5.0
H3 H4 H3
7.5
H3 H4 H3
6.1
H3 H4 H3 H4
4.3
H3 H4 H3 H4
6.0
H3 H4 H3 H4
5.3
8.2
6.9
23.3
1.0
8.6
33.7
5.7
6.4
21.0
10.1
29.9
6.3
22.2
10.1
30.0
7.5
6.3
23.2
1.6
10.2
30.6
9.9
6.2
23.1
1.8
9.9
30.1
10.3
6.6
22.7
9.9
30.2
6.2 2.6
5b cis trans
4.9 5.3
5c cis trans
a 0.7
3.1
5d cis trans cis
Table 1. Aldol Reaction of Cyclic Germanium Enamine 3 with Various Aldehydes" entry
aldehyde CC13CHO MeCHO EtCHO PhCHzCHO PhCHO m-ClPhCHO m-ClPhCHO m-ClPhCHO
Sa
2.4 1.7
5e
5
aldol product
9.2
yield (%)b
diasteromer ratioCcis:trans
87 82 79 78 90 90 87 89
4:96 26:74 35:65 28:72 7525 75:25 76:24 71:29
5b 5c 5d 5e 5f 5f 5f a Reaction was carried out in toluene at rmm temperature under argon. Isolated yield. Determined by *H NMR.
of the trimethylsilyl groups and the olefins in the l-azacyclohexa-3,5-diene(six-membered ring) moiety, respectively. The 13C NMR spectrum also supported the bicyclic germanium enamine structure 3. These results clearly show that germylene 1, having a bulky electrondonating group on the germanium atom, has a strong nucleophilicity toward the carbon-carbon double bond conjugated with the pyridine ring. It is to be noted that the pyridine structure is destroyed and transformed t o the bicyclic enamine structure as a result of the germanium-carbon bond formation at the terminal vinyl carbon of 2-vinylpyridine and the germanium-nitrogen bond formation. Aldol Type Reaction of 3 with Aldehydes. The germanium enamine 3 showed nucleophilic reactivity, which is characteristic of a metal-enamine compound. When the enamine 3 was treated with an aldehyde 4 which acts as an electrophile in toluene a t room temperature, an aldol type reaction took place smoothly t o afford a l-oxa-2-germacyclopentane derivative 5 having a pyridyl group and an alkyl group at the 4 and 5 positions, respectively (Scheme 2). The yield of the aldol reaction and the diastereomer ratio (cis:trans) of the condensation product 5 are summarized in Table 1. All the reactions proceeded smoothly at room temperature t o give 5 in good yield (78-90%). The nucleophilic attack at the aldehyde takes place regioselectively at the carbon-carbon double bond in the five-memberedring of 3. At the same time, cleavage of the germanium-nitrogen bond occurs, regenerating the pyridine ring. It is assumed that the stabilization due to the aromaticity of the pyridine is an important driving force to promote the aldol reaction.
trans
11.0 2.9 1.8
5f cis trans
10.6 1.1
1.1
2.5
NOE was not detected because of the short distance between H3 and H4.
The aldol reaction was found to proceed in a stereoselective manner. When aliphatic aldehydes were used as electrophiles, trans isomers were obtained preferentially (entries 1-4). Especially, a product of higher diastereoselectivity (cis:trans = 4:96) was obtained with chloral (trichloroacetaldehyde)as the electrophile (entry 1). Treatment of 3 with aromatic aldehydes (benzaldehyde and m-chlorobenzaldehyde) also gave the corresponding condensation products in good yield. In this case, the cis isomers were obtained predominantly (entries 5-8). The diastereomeric ratio of the aldol product was determined by comparing the integral values of the peaks due to the methyne proton (4 positions) of 5 in the lH NMR spectrum of the mixture of cis and trans isomers (cis isomer, 6 3.59-3.93; trans isomer, 6 2.93-3.52). The resulting l-oxa-2-germacyclopentane derivative 5 was found to be stable at room temperature, and each diastereomer can be separated by silica gel column chromatography without decomposition. Structure Determination of Aldol Product 5. The relative configuration (cis:trans) between the pyridyl group at the 4 position and the alkyl group a t the 5 position of the product 5 was determined by a nuclear Overhauser effect (NOE) measurement on the lH NMR spectra (Table 2). For example, when the signal derived from the proton on carbon 4 (denoted by H3 in Figure 1) of product 5e was irradiated, the spectrum of the main isomer showed a larger NOE between H3and H4 (9.9%). Irradiation of the proton on carbon 5 (denoted by H4in Figure 1) also caused a large NOE (11.0%) observation between H3and H4. These results clearly indicate that proton H3 and proton H4are located close each other, suggesting that these substituents on the 4 and 5 positions of the main isomer have a cis relationship. On the other hand, the minor isomer showed a indicating that smaller NOE (1.8%)between H3 and H4,
A Cyclic Germanium Enamine n
Organometallics, Vol. 14, No. 12, 1995 5535
H 4 - T
cis- 5e
trans- 5e
Figure 1. NOE of aldol products cis-5e and trans-5e. Scheme 3
f,R'
H:
.* '
6
L
7
Concerning the stereoselectivity of the present reaction, the preferential formation of the trans isomer can be explained by assuming an acyclic transition state 6,1° where a chelate formation between Ge and oxygen does not occur because of the lower Lewis acidity of the germanium atom having bulky electron-donating groups. As mentioned above, the use of benzaldehyde or mchlorobenzaldehyde as the electrophile affords the cis isomer preferentially. These results suggest that the reaction proceeds via a different transition state in the case of an aromatic aldehyde. The transition state 8 may be preferable due to the n-n interaction between part of the enamine and the l-azacyclohexa-3,5-diene benzene ring of the aldehyde, leading to the preferential formation of the cis isomer via the intermediate 9.
I
Conclusion R' ,o+lIH
trans-5
9
cis-5
the relative configuration of these substituents is trans. The structure determinations of other products (5a-d and 5f) were carried out in a similar manner. In addition to the NOE measurements, the coupling constant between H3 and H4 (J(H3-H4)) as well as the l3C chemical shift of the methylene carbon adjacent to the germanium atom (GeCH2)also give useful information about the structure of cis and trans isomers (Table 2). The coupling constants (J(H3-H4)) of the trans isomer are 8.6-10.2 Hz, whereas those of cis isomer show smaller values of 6.2-6.9 Hz. The chemical shifts for the carbon atoms adjacent t o the germanium atom in the two isomers show a remarkable difference; the chemical shift values for the cis isomer are 21.0-23.3 ppm whereas those of trans isomer are 29.9-33.7 ppm. These NMR parameters are especially useful to confirm the relative configuration of the product 5c whose NOE can only be partly detected. Reaction Mechanism. At present, the formation of the 1-oxa-2-germacyclopentaneskeleton 5 may be explained as follows (Scheme 3). The nucleophilic attack of germanium enamine 3 on the aldehyde takes place regioselectively at the carbon atom on the five-membered ring to give a corresponding zwitterionic intermediate 7 (or 9) having an alkoxide ion and a germanium cation. Then, this intermediate undergoes a nucleophilic intramolecular attack of the alkoxide ion at the germanium cation giving rise to the cyclic aldol product 5.
The oxidative addition of 2-vinylpyridine t o the germylene bis[bis(trimethylsilyl)aminatolgermanium( 11) gave a novel bicyclic germanium enamine having a l-azacyclohexa-3,5-dienestructure. The resulting enamine was successfully condensed with various aldehydes via an aldol type reaction giving rise t o the corresponding 4,5disubstituted 1-oxa-2-germacyclopentanederivatives in good yield. To our best knowledge, the present reaction is the first example of a carbon-carbon bond-forming reaction using a cyclic germanium enamine species which can be constructed by a redox process starting from a divalent germanium compound, a germylene. It is also to be noted that the aldol product is a new l-oxa2-germacyclopentane derivative having a pyridyl group and an alkyl group at the 4 and 5 positions, respectively, where the stereochemistry of these groups can be fairly well controlled. The skeleton of the resulting 4,5disubstituted 1-oxa-2-germacyclopentane is very difficult to construct by the conventional methodology of using a germanium(IV1compound as starting material. Experimental Section General Procedure. The germylene bis[bis(trimethylsilyl)aminato]germanium(II) (1) was prepared according to the literature.* 2-Vinylpyridine and aldehydes were distilled over calcium hydride. Toluene was purified by distillation from benzophenone ketyl before use. All reactions were carried out under an argon atmosphere. Column chromatography was performed with silica gel 60 (70-230 mesh) (Merck). NMR spectra (lH and I3C) were recorded on a Brucker AM-250T spectrometer. Preparation of Germanium Enamine 3. A solution of bis[bis(trimethylsilyl)aminato]germanium(II)(1) (65 mg, 0.17 mmol) in C& (0.2 mL) was added to a solution of 2-vinylpyridine (2) (17 mg, 0.16 mmol) in CsD6 (0.3 mL) a t room temperature under argon. The reaction mixture was transferred to a NMR sample tube, and the formation of the germanium enamine 3 was directly confirmed by NMR spectroscopy (95% yield determined by 'H NMR): 'H NMR (C&) 6 0.36 (s, SiMe3, 36H), 1.84 (d, J = 3.6 Hz, CH2, 2H), 4.33 (t, J = 3.6 Hz, -CH2CH=C, lH), 4.3-7.1 (m, olefin, 4H); I3C NMR (C&) 6 5.9 (SiMes), 25.4 (CHz), 84.6 (-CHzCH=C), 101.0, 121.4, 128.0, 137.8, 148.6. Aldol Type Reaction of 3 with Aldehydes. To a toluene solution (1.6 mL) of the germylene 1 (0.631 g, 1.60 mmol) was added a toluene solution (1.6 mL) of 2-vinylpyridine (2) (0.173 g, 1.64 mmol) a t 0 "C, and the reaction mixture was stirred (10)Noyori, R.; Nishida, I.; Sakata, J. J.Am. Chem. SOC.1983,105, 1598.
Iwata et al.
5536 Organometallics, Vol. 14, No. 12, 1995
JBX = 6.7 Hz, CHpJle, lH), 1.99 (dd, JAB = 13.2 Hz, Jpx = 11.2 for 15 min. To this mixture was added a toluene solution (1.6 = 3.5 Hz, CHAHBHz, CHAHB,lH), 2.24 (dd, JAB= 14.2 Hz, JBX mL) of chloral (0.240 g, 1.63 mmol) in toluene (1.6 mL) at 0 Ph, lH), 2.46 (dd, JAB= 14.2 Hz, Jpx = 9.2 Hz, CHAHBPh, "C. After being stirred for 15 min, the reaction mixture was = 3.5 Hz, Jxy = 6.3 Hz, OCHy, lH), 3.72 (ddd, Jpx = 9.2 Hz, JBX concentrated to dryness. The residue was dissolved in CDC13, lH), 7.1-8.6 (m, pyridyl, phenyl, 9H); I3C NMR (CDCl3)6 5.5, and an 'H NMR spectrum of the condensation products was 5.6 (SiMes), 23.2 (GeCHd, 39.2 (CHzPh), 49.6 (CHzCHx), 77.9 taken in order to determine the diastereomer ratio (cis:trans). (OCHy), 121.4, 122.6 (py C3, 51, 125.3, 127.6, 129.1 (Ph, C2After recovery of the products, each diastereomer was sepa61, 135.9 (py, C4), 140.0 (Ph, Cl), 149.2 (py, C6), 161.3 (py, rated by silica gel column chromatography (e1uent:n-hexanel C2). diethyl ether = 5/11 to give 0.041 g of the cis isomer and 0.882 Trans isomer: 'H NMR (CDC13)6 0.09 (s, SiMes, 18H),0.29 g of the trans isomer. (s, SiMe3,18H), 1.60 (dd, JAB = 13.4 Hz, JBX = 13.2 Hz, CHAHB, Aldol Product 5a. Cis isomer: 'H NMR (CDC13) 6 0.30 = 13.4 Hz, Jpx = 6.9 Hz, CHAHB,lH), 2.65 l H ) , 1.85 (dd, JAB (s, SiMe3, 18H), 0.33 (8,SiMe3, 18H), 1.41 (dd, JAB = 13.1 Hz, (dd, JAB = 13.7 Hz, JBX = 8.5 Hz, CHdBPh, lH), 2.72 (dd, JBX = 6.8 Hz, -CH&B, lH), 2.44 (dd, JAB 13.1 Hz, Jpx = JAB = 13.7 Hz, Jpx = 2.5 Hz, CHAHBPh, lH), 3.09 (ddd, J m = 13.7 Hz, CHAHB,lH), 3.91 (ddd, Jpx = 13.7 Hz, JBX = 6.8 Hz, 6.9Hz,Jsx=13.2Hz, Jxy=10.2Hz,CHzCHx, lH),4.14(ddd, Jxy = 6.9 Hz, -CHzCHx-, lH), 4.83 (d, Jxy = 6.9 Hz, CHyJ m = 2.5 Hz, JBX = 8.5 Hz, Jxy = 10.2 Hz, OCHy, lH), 7.10, lH), 7.1-8.7 (m, pyridyl, 4H); I3C NMR (CDC13) 6 5.5 8.6 (m, pyridyl, phenyl, 9H); 13C NMR (CDC13) 6 5.3, 5.7 (SiMes), 23.3 (CHz), 50.2 (CHzCH), 86.5 (QCH), 102.6 (CC13), (SiMea), 30.0 (GeCHd, 41.6 (CHzPh), 53.1 (CH~CHX), 79.6 122.2, 123.1 (Py, C3, C5), 135.9 (py, C4), 149.0 (py, C6), 159.0 (OCHy), 121.4, 122.5 (py, C3, 51, 125.5, 127.6, 129.6 (Ph, C2(py, C2). 61, 136.2 (py, C4), 140.0 (Ph, Cl), 149.6 (py, C6), 163.0 (py, Trans isomer: 'H NMR (CDC13) 6 0.31 (s, SiMea, 18H), 0.32 C2). (s, SiMe3,18H), 1.57 (dd, JAB = 13.6 Hz, JBX = 13.2 Hz, CHPJIB, Aldol Product 5e. Cis isomer: 6 0.33 (s, SiMes, 18H), 0.34 lH), 2.16 (dd, JAB = 13.6 Hz, Jpx = 7.2 Hz, CHAHB,lH), 3.52 (s, SiMe3,18H), 1.35 (dd, JAB = 12.7 Hz, JBX = 5.8 Hz, CHAHB, (ddd, Jpx = 7.2 Hz, JBX= 13.2 Hz, Jxy = 8.6 Hz, CHzCHx, = 12.7 Hz, Jpx= 12.4 Hz, CHAHB,lH), 3.93 lH), 1.76 (dd, JAB ~ 8.6 Hz, OCH, lH), 7.1-8.6 (m, pyridyl, 4H); lH), 5.02 (d, J x = = 5.8 Hz, Jxy = 6.2 Hz), 5.47 (d, Jxy (ddd, Jpx = 12.4 Hz, JBX 13C NMR (CDC13) 6 5.30, 5.66 (SiMea), 33.7 (CHd, 49.7 = 6.2 Hz, OCHY, lH), 6.6-8.6 (m, pyridyl, phenyl, 9H); I3C (CHzCH), 88.3 (OCH), 103.6 (CC13), 121.3, 123.2 (py, C3, C5). NMR (CDC13) 6 5.4, 5.5 (SiMes), 23.1 (CHZ),51.3 (CHZCHX), Anal. Calcd for C ~ I H ~ ~ C ~ ~ GC,~39.05; N~O H,S6.87; ~ ~ N, : 6.51; 79.4 (OCHy), 121.3, 122.0 (py, C3, C5),126.3, 126.8, 126.9 (Ph, C1, 16.47. Found: C, 39.00; H, 6.96; N, 5.92; C1, 16.61. C2-6), 135.5 (py, C4), 141.2 (Ph, Cl), 148.8 (py, C6), 160.1 (py, Aldol type reaction using other aldehydes were carried out C2); IR 1582,1461,1426,1399,1249,1021,895,869,769,734, in a similar manner to afford the corresponding condensation 702, 672, 647 cm-I. Anal. Calcd for C26H49GeN30Si4: C, products. 51.65; H, 8.17; N, 6.95. Found: C, 51.32; N, 8.27; N, 6.67. Aldol Product 5b. Cis Isomer: 'H NMR (CDC13) 6 0.30 Trans isomer: 'H NMR (CDC13) 0.32 (s, SiMeg, 18H), 0.35 (s, SiMe3, 18H), 0.31 (s, SiMe3, 18H),0.72 (d, J = 6.4 Hz, CH3, (s, SiMe3, MH), 1.88 (dd, JAB = 13.3 Hz, JBX = 12.9 Hz, CHAHB, 3H), 1.34 (dd, JAB = 12.9 Hz, JBX = 6.3 Hz, CHAHB,lH), 1.93 lH), 2.00 (dd, JAB = 13.3 Hz, Jpx = 6.9 Hz, CHAHB,lH), 3.13 = 12.9 Hz, Jpx = 13.0 Hz, CHAHB,lH), 3.59 (ddd, J m (dd, JAB = 12.9, Jxy = 9.9 Hz, CHzCHx, lH), 4.96 (ddd, Jpx = 6.9, JBX = 13.0 Hz, JBX = 6.3 Hz, Jxy = 6.4 Hz, CH~CHX, lH), 4.58 ~ 9.9 Hz, OCHY,lH), 6.6-8.6 (m, pyridyl, phenyl, 9H); (d, J x = = 6.4 Hz, OCHY, lH), 7.1-8.6 (m, (dq, Jm = 6.4 Hz, JM~-w I3C NMR (CDC13) 6 5.43, 5.73 (SiMea), 30.1 (CHz), 56.0 pyridyl, 4H); 13CNMR (CDCl3) 6 5.53, 5.66 (SiMea), 18.7 (Me), (CHzCHx),81.2 (OCHy), 121.3, 123.6 (py, C3, C5), 126.3, 126.7, 21.0 (CH2), 49.8 (CHzCH), 73.4 (OCH), 121.3, 122.1 (py, C3, 127.5 (Ph, C2-61, 135.7 (py, C4), 143.8 (Ph, Cl), 149.4 (py, C6), C5), 136.0 (py, C4), 149.2 (py, C6), 161.5 (py, C2). Anal. Calcd 161.8 (py, C2); IR 1581, 1428, 1250, 1010, 876, 854, 761, 701, for C21H47GeN30Si4:C, 46.49; H, 8.73; N, 7.74. Found: C, 672 cm-'. Anal. Calcd for C26H49GeN30Si4: C, 51.65; H, 8.17; 46.06; H, 8.84; N, 7.63. N, 6.95. Found: C, 51.59; H, 8.14; N, 6.94. Trans isomer: 'H NMR (CDC13)6 0.29 (s, SiMe3, 36H), 1.13 Aldol Product 5f. Cis isomer: 'H NMR (CDC13)6 0.33 (s, = 13.5 Hz, JBX = 12.8 (d, J = 5.9 Hz, CH3, 3H), 1.68 (dd, JAB SiMe3, 0.36 = 12.7 Hz, ~ ~ =18H), ~.~ H z(s,,SiMe3, C H A18H), H B ,1.35 (dd, JAB Hz,CH&B, ~ H ) , ~ . ~ ~ ( ~ ~ , J A B = ~ ~ . ~ H z , J JB~=~.~Hz,CHAHB,~H),~.~~(~~,JAB= lH), 2.93 (ddd, Jpx = 7.2 Hz, JBX = 12.8 Hz, Jxy = 10.1 Hz, Hz, CHAHB,lH), 3.92 (ddd, Jpx = 12.8 Hz, JBX = 5.7 Hz, Jxy CHzCHx, lH), 4.00 (dq, Jxy = 10.1 Hz, JM~-HY = 5.9 Hz, OCHy, = 6.6 Hz, CHzCHx lH), 5.44 (d, Jxy = 6.6 Hz, OCHy, lH), 6.7lH), 7.1-8.5 (m, pyridyl, 4H); 13C NMR (CDC13) 6 5.4, 5.7 8.5 (m, pyridyl, phenyl, 9H); 13C NMR (CDC13) 6 5.4, 5.5 (SiMes), 21.4 (CH31, 29.9 (CH2), 55.1 (CHzCH), 75.0 (OCH), (SiMed, 22.7 (CH2), 51.2 (CHzCH), 79.0 (OCH), 121.5, 121.9 121.3, 122.4 (py, C3, C5), 136.1 (py, C4), 149.5 (py, C6), 163.1 (py, C3, C5), 125.0, 126.5, 126.7, 128.1 (Ph, C2, 4, 5, 61, 133.3 (py, C2). Anal. Calcd for C21H47GeN30Si4: C, 46.49; H, 8.73; (Ph, Cl), 135.7 (py, C4), 143.7 (Ph, C3), 148.9 (py, C6), 160.5 N, 7.74. Found: C, 46.49; H, 8.56; N, 7.65. (py, C2). Anal. Calcd for C26H4&1GeN30Si4: C, 48.87; H, Aldol Product 5c. Cis isomer: 'H NMR (CDC13) 6 0.27 7.57; N, 6.58; C1, 5.55. Found: C, 48.44; H, 7.86; N, 6.44; C1, (s, SiMe3, 18H), 0.29 (s, SiMe3,18H), 0.77,0.79 (CH3,3H), 0.95.62. 1.1 (m, MeCH2, 2H), 1.35 (dd, JAB= 12.9 Hz, JBX = 6.8 Hz, Trans isomer: lH NMR (CDC13) 6 0.32 (s, SiMe3, 18H), 0.35 = 12.9 Hz, Jm = 12.7 Hz, GeCHAHB, lH), 1.89 (dd, JAB (s,SiMe3, 18H), 1.85 (dd, JAB = 13.5 Hz, JBX = 13.3 Hz, CHAHB, = 12.7 Hz, JBX = 6.8 Hz, J x y = GeCHAHB, lH), 3.64 (ddd, JAX lH), 2.00 (dd, JAB = 13.5 Hz, J m = 6.7 Hz, CHAHB,lH), 3.07 6.3 Hz, CH~CHX, lH), 4.19 (m, OCHy, lH), 7.1-8.6 (m, pyridyl, (ddd, Jpx = 6.7 Hz, JBX = 13.3 Hz, J x y = 9.9 Hz, CHzCHx, 4H); NMR (CDC13) 6 5.48, 5.69 (SiMes), 10.8 (CH31, 22.2 lH), 4.98 (d, JXY= 9.9 Hz, OCHy, lH), 6.7-8.6 (m, pyridyl, (GeCHd, 25.6 (MeCHZ), 49.6 (CH~CHX), 78.6 (OCH), 121.3, phenyl, 9H); NMR (CDC13) 6 5.4, 5.7 (SiMea), 30.2 (CHZ), 122.3 (py, C3, C5), 135.9 (py, C4), 149.2 (py, C6), 161.6 (py, 56.0 (CHzCH), 80.5 (OCH), 121.6, 123.6 (py, C3, C5), 124.3, C2). Anal. Calcd for C22H49GeN30Si4: C, 47.48; H, 8.87; N, 126.4, 126.8, 128.7, (Ph, c 2 , 4, 5, 61, 133.6 (Ph, Cl), 135.8 (py, 7.55. Found: C, 47.08; H, 8.87; N, 7.35. C4), 146.3 (Ph, C3), 149.6 (py, C6), 161.4 (py, C2). Anal. Calcd Trans isomer: 'H NMR (CDC13)6 0.29 (s, SiMe3, 36H),0.93 for CzsH48ClGeN30Si4: C, 48.87; H, 7.57; N, 6.58; C1, 5.55. (t, CH3, 3H), 1.2-1.4 (m, MeCH2, 2H), 1.62 (dd, JAB = 13.3 Found: C, 48.36; H, 7.77; N, 6.49; C1, 5.85. Hz, JBX = 13.0 Hz, GeCHAHB, lH), 1.81 (dd, JAB = 13.3 Hz, Jpx = 6.8 Hz, GeCffAHB, lH), 2.97 (ddd, J m = 6.8 Hz, JBX =
Acknowledgment. ~~.OH~,J~=~O.~H~,CH~CHX,~H),~. ~ ~ ( ~ , J X ~ = ~This O . work ~ H Z was , partially supported by a Grant-in Aid for Scientific Research on Priority Area (07216209) and a Grant-in Aid for Scientific Research (06453145). We thank Asai Germanium Research Institute for providing us with germanium tetrachloride.
OCHY, lH), 7.1-8.5 (m, pyridyl, 4H); NMR (CDC13) 5.4, 5.7 (SiMea), 11.0 (CH31, 28.6, 30.0 (CHZ),53.5 (CH~CHX), 80.1 (OCH), 121.3,122.4 (py, C3, C5), 136.0 (py, C4), 150.0 (py, C6), 163.2 (py, C2). Anal. Calcd for CZ2H49GeN30Si4:C, 47.48; H, 8.87; N, 7.55. Found: C, 47.29; H, 9.02; N, 7.38. Aldol Product 5d. Cis isomer: 'H NMR (CDC13) 6 0.24 (s, SiMe3, 18H), 0.29 (s, SiMes, 18H), 1.48 (dd, JAB = 13.2 Hz,
OM950559L
