Metallic Base-Induced Cycloadditions of<i>N</i>-(1-Cyanoalkyl)imines via<i>N</i>-Metalated Azomethine Ylides: Enhanced Reactivity and High Regio- and Stereoselectivity
Lithiation of N-(1-cyanoalkyl)imines with LDA generates new N-lithiated azomethine ylide 1,3-dipoles which show enhanced reactivity toward dipolarophiles. They undergo exclusively regio- and stereoselective 3+2 cycloaddition reaction with α,β-unsaturated esters to give 1-pyrrolines after the elimination of LiCN. Metallic bases other than LDA can be also effective. Such high regio- and stereoselectivity is explained by the involvement of N-metalated azomethine ylides.
Gundermann,K.-D. et al., Chemische Berichte, 1972, vol. 105, p. 312 - 324
作者:Gundermann,K.-D. et al.
DOI:——
日期:——
Direct vinylation of 2-substituted N-(Benzylidene)glycinonitriles under basic conditions
作者:Andrzej Jończyk、Zbigniew Pakulski
DOI:10.1016/s0040-4039(96)02045-x
日期:1996.12
alpha-Vinyl substituted nitriles 5-7 were prepared via addition of carbanions generated from nitriles 1, to acetylene (2) and its derivatives 3 and 4. Subsequent cleavage of nitriles 6 and 7 afforded alpha,beta-unsaturated ketones 8 and 9. Copyright (C) 1996 Elsevier Science Ltd
Michael Addition and Alkylation of 2-Azaallyl Anions Derived from<i>N</i>-(1-Cyanoalkyl)imines, and Stereoselective Cyclization of Imine Esters or Ketones Leading to 1-Pyrrolines
The 2-azaallyl anionsderivedfrom N-(1-cyanoalkyl)imines and DBU undergo Michael addition or alkylation to produce N-(1-alkylated 1-cyanoalkyl)imines. The Michael addition of some aryl-substituted imines are highly diastereoselective. The alkylated Michael adducts are converted into lactams through a hydrolysis and recyclization sequence. Base-induced cyclization furnishes 1-pyrrolines through a cyclization