Sterically shielded secondary N-tritylamines and N-tritylamide bases, readily available and useful synthetic reagents
摘要:
t-Butyltritylamine (1) and lithium t-butyltritylamide (2) are introduced as readily available and useful superhindered bases. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.
elimination of hydrogen chloride from amide or sulfonamide derivatives of o-(chloromethyl)aniline, has never been reported. This powerful approach provides easy and stereoselective access to polycyclic hydroquinolines, as shown for an example in Equation (1).
Reaction of -silyl imines with silyi keteneacetals in the presence of ZnI2 and t-butyl alcohol, followed by treatment of the intermediate -silyl β-aminoesters with MeMgBr, produces -silyl-azetidin-2-ones in good yield; use of trimethylsilyl triflate as Lewis acid catalyst can be advantageous in some cases. The preparation of the -t-butyldimethylsilyl imine of ethyl glyoxylate in this context is detailed
Reaction of silyl ketene acetals with N-trimethylsilyl imines: a route to N-unsubstituted azetidin-2-ones
作者:Ernest W. Colvin、Daniel G. McGarry
DOI:10.1039/c39850000539
日期:——
Reaction of N-trimethylsilylimines with silylketeneacetals in the presence of ZnI2 and t-butyl alcohol, followed by treatment in situ of the intermediate N-silyl β-aminoesters with MeMgBr, leads to N-unsubstitutedazetidin-2-ones in good yield.
Highly selective, kinetically controlled enolate formation using lithium dialkylamides in the presence of trimethylchlorosilane
作者:E.J. Corey、Andrew W. Gross
DOI:10.1016/s0040-4039(00)99920-9
日期:1984.1
The deprotonation of ketones and esters with lithium dialkylamides in the presence of trimethylchlorosilane leads to enhanced selectivity for the kinetically generated enolate. Lithium -octyl--butylamide is shown to be superior to lithiumdiisopropylamide in the regio-selective generation of enolates and in the stereoselective formation of enolates.
An efficient method for one-pot synthesis of β-lactams from aldimines and ketene silyl acetals by tandem Lewis base-catalyzed Mannich-type addition and cyclization, namely reaction of benzylideneanilines and trimethylsilyl enolates derived from esters or thioesters was established by using a Lewis base catalyst such as lithium acetate, N-lithio-2-pyrrolidone, potassium salt of phthalimide or lithium