Alkylation and aldol reactions of acyl derivatives of N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine: asymmetric synthesis of α-alkoxy-, α-substituted-β-alkoxy- and α,β-dialkoxyaldehydes
摘要:
Treatment of a range of O-protected glycolate derivatives of the chiral auxiliary N-1-(1'-naphthyl)ethyl-O-tert-butylhydroxylamine with KHMDS in the presence of 18-crown-6 followed by addition of an alkyl halide generates alpha-substituted derivatives with very high levels of diastereoselectivity. Alternatively, reaction of the potassium enolate of a propanoate or O-protected glycolate derivative of N-1-(1'-naphthyl)ethyl-O-tert-butylhydroxylamine with a range of aldehydes gives syn-aldol products with high levels of diastereoselectivity. These adducts may be reductively cleaved with LiAlH(4) to give enantiopure alpha-alkoxy-, alpha-substituted-beta-alkoxy- and alpha,beta-dialkoxyaldehydes in good yield. (C) 2010 Elsevier Ltd. All rights reserved.
A new approach for the stereoselective synthesis of the piperidine alkaloid (+)-beta-conhydrine based upon a highly diastereoselective 1,2-nucleophilic addition reaction onto a diastereopure hydrazone and ring-closing metathesis as the key steps has been developed. (C) 2008 Elsevier Ltd. All rights reserved.
Steric and Electronic Effects in Conformational Preferences of C1-Oxygenated Chiral Alkenes
作者:Benjamin W. Gung、Jason P. Melnick、Mark A. Wolf、Amanda King
DOI:10.1021/jo00112a012
日期:1995.4
A variable temperature NMR study shows that the benzyl protective group on the hydroxy function of a chiral allylic alcohol enhances the CH eclipsed form (I). On the other hand, various silyl ethers enhance the preference for the CO eclipsed conformer. However, when both the allylic R group and the hydroxy protective group are bulky (R tert-butyl, P = TIPS), the staggered conformation of the chiral alkene becomes preferred. An acetate group does not have an apparent effect on the conformational preference of the protected allylic alcohol. These facts are explained in terms of steric and electronic interactions.
SUBSTITUTED SPIROPYRIDO[1,2-a]PYRAZINE DERIVATIVE AND PHARMACEUTICAL USE OF SAME AS HIV INTEGRASE INHIBITOR
申请人:Japan Tobacco Inc.
公开号:US20160046641A1
公开(公告)日:2016-02-18
[Problem] Provided is a substituted spiropyrido[1,2-a]pyrazine derivative or a pharmaceutically acceptable salt thereof, which is useful as an anti-HIV agent.
[Solving Means] The present invention relates to a compound represented by the following formula [I] or [II] or a pharmaceutically acceptable salt thereof:
wherein each symbol is as defined in the specification.