Stereoselective synthesis of 3-(ω-hydroxyalkyl)-2-pyrrolidinones from α-alkylidenelactones and nitromethane
摘要:
Enantiopure 3-(omega-hydroxyalkyl)-2-pyrrolidinones 7 and 9 were synthesised by Michael-addition of nitromethane to chiral alpha-alkylidenelactones 1 followed by reduction of the resulting 3-(beta-nitroalkyl)-lactones and ring transformation of the intermediate 3-(beta-aminoalkyl)-lactones. In an analogous manner the naturally occurring costuslactone 10 was transformed into the butyrolactam 12. (C) 1999 Elsevier Science Ltd. All rights reserved.
Stereoselective radical additions of γ-oxy-α,β-unsaturated ester derivatives; 1,2-asymmetric induction in acyclic and cyclisation systems
摘要:
Examination was made of 1,2-asymmetric induction in the addition of alkyl radicals to gamma-oxy-alpha,beta-unsaturated ester derivatives 1 and 2 prepared from ethyl lactate and (R)-2,3-0-isopropylideneglyceraldehyde 3, respectively. The addition reactions of hexyl, cyclohexyl and 3-phenylpropyl radicals to (Z)-2 derived from aldehyde 3 gave beta-addition products with syn-stereoselectivity (syn:anti = 8.6:1-syn only). The reactions of (E)-2 were non-stereoselective. Based on allylic strain, a transition-state model for the syn-stereoselectivity is proposed. 1,2-Asymmetric induction was carried out in radical cyclisation to synthesize optically active cyclohexane derivatives.
Synthesis of optically active hydroxyalkylbenzothiazepinones by ring transformation of 2-alkylidenelactons with<i>o</i>-aminothiophenol
作者:Andreas Otto、Jürgen Liebscher
DOI:10.1002/jhet.5570370436
日期:2000.7
A stereoselectivesynthesis of new opticallyactive3-(hydroxyalkyl)-2,3-dihydro-1,5-benzothiazepin-4-ones 4 and 7 was achieved by Michael-like addition of o-aminothiophenol to chiral α-alkylidenelactons 1 and 5 followed by ring chain transformation of the resulting adducts 3 and 6.