Journal of the Chemical Society. Perkin Transactions 2 (2001) p. 1171 - 1196 (1996)
Update date:2022-08-03
Topics:
Fleming, Ian
Jones, Graeme R.
Kindon, Nicholas D.
Landais, Yannick
Leslie, Colin P.
Morgan, Ian T.
Peukert, Stefan
Sarkar, Achintya K.
The homochiral pentadienylsilanes (3Z,5E)-(hepta-3,5-dien-2-yl)dimethyl(phenyl)silane 9, (3Z,5E)-(hepta-3,5-dien-2-yl)trimethylsilane 13, (4Z,6E)-(2-methylocta-4,6-dien-3-yl)dimethyl(phenyl)silane 14 and (4Z,6E)-(2-methylocta-4,6-dien-3-yl)trimethylsilane 17 undergo Lewis acid catalysed reactions with isobutyraldehyde and its dimethyl acetal stereospecifically anti with surprisingly high levels of stereoselectivity, ca. 90:10. The pentadienylsilanes (3Z)-hexa-3,5-dien-2-yldimethyl(phenyl)silane 20aa, (4Z)-(2-methylhepta-4,6-dien-3-yl)dimethyl(phenyl)silane 20ab, (3Z)-(hexa-3,5-dien-2-yl)-trimethylsilane 20ba and (2Z)-(1-phenylpenta-2,4-dienyl)trimethylsilane 20bc undergo dipolar cycloadditions to 2,2-dimethylpropanenitrile oxide regioselectively at the terminal double bond and stereoselectively anti to the silyl group to a somewhat lower extent, ca. 70:30. The pentadienylsilane (3Z,5E)-(6-cyclohexylhexa-3,5-dien-2-yl)trimethylsilane 25 undergoes deuteriodesilylation stereospecifically anti to a lower extent still, ca. 55:45. The pentadienylsilane (3Z,5E)-(8-methyl-8-methoxyethoxymethoxynona-3,5-dien-2-yl)trimethylsilane 34 undergoes an intramolecular reaction stereospecifically anti again to the extent of about 60:40, whereas the reaction of the corresponding allylsilane (3Z)-(6-methyl-6-methoxyethoxymethoxyhept-3-en-2-yl)trimethylsilane 32 is essentially completely anti. These results show that SE2″ reactions can be highly stereoselective in the anti sense, that the high level is probably best accounted for by the steric effect of the silyl group, and that when the steric effect is minimised, the stereospecificity is low, but still measurable. The pentadienylsilanes were prepared by aldol reactions between β-silyl esters and the appropriate α,β-unsaturated aldehyde, followed by decarboxylative elimination. The products of the SE2″ reactions were identified and their stereochemistry determined by comparison with authentic materials or by degradation and synthesis, using chiral auxiliaries to determine the enantiomeric purity. The products of two of the dipolar cycloadditions were identified by degradation and stereospecific vinylogous Peterson elimination, but the vinylogous Peterson elimination taking place with (1RS,2Z,4SR,6SA)-(4,6-dihydroxy-7,7-dimethyl-1-phenyloct-2-enyl)trimethylsilane 67bc and its (1SR) diastereoisomer 68bc was not stereospecific, giving (5E,7E)-2,2-dimethyl-8-phenylocta-5,7-dien-3-ol 73 from both isomers. The stereochemistries of all the reactions are summarised.
View MoreMollt Biochem Co., Ltd(expird)
Contact:+86-21-38682181
Address:shanghai ,china
Tianjin Pharmacn Medical Technology Co.,Ltd.
Contact:86-22-60122566ext.866(English),23359620
Address:Green Industrial Base, 6 Haitaifazhan Sixth Rd., Huayuan Industrial Area, Tianjin, 300384, China
Jiaxing Trustworthy Import And Export Co.,Ltd
Contact:+86-573-82030555
Address:Room 1202, Unit B, Charming plaza,No.1558 East Zhongshan Road , Jiaxing City, Zhejiang Province, China.
Tianjin Chemsyntech Chemical Co., Ltd
Contact:+86-22-60872258
Address:Haitai green industry base in Tianjin, K1,5-601
website:http://www.maisonchem.com.cn
Contact:0086-311-83833777
Address:Leitou industrial district, xinji, shijiazhuang city, hebei province,
Doi:10.1016/j.molstruc.2017.09.092
(2018)Doi:10.1016/0022-328x(96)06125-6
(1996)Doi:10.1016/0040-4039(96)00737-X
(1996)Doi:10.1016/S0040-4039(00)97173-9
(1990)Doi:10.1021/jo991397w
(2000)Doi:10.1021/acs.orglett.5b00261
(2015)
