Reaction of <i>N</i>-Vinylic Phosphazenes with α,β-Unsaturated Aldehydes. Azatriene-Mediated Synthesis of Dihydropyridines and Pyridines Derived from β-Amino Acids
作者:Francisco Palacios、Esther Herrán、Concepción Alonso、Gloria Rubiales、Begoña Lecea、Mirari Ayerbe、Fernando P. Cossío
DOI:10.1021/jo060775b
日期:2006.8.1
Aza-Wittig reaction of N-vinylic phosphazenes (1,2 addition), derivedfrom diphenylmethylphosphine or derivedfrom trimethylphosphine with α,β-unsaturated aldehydes, leads to the formation of 3-azatrienes through a [2 + 2]-cycloaddition−cycloreversion sequence. The presence of an alkyl substituent in position 3 of N-vinylic phosphazenes increases the steric interactions, and [4 + 2] periselectivity
Aza-Wittig reaction of N-vinylic phosphazenes with alpha,beta-unsaturated aldehydes leads to the formation of 3-azatrienes through a [2+2]-cycloaddition-cycloreversion process. Subsequent, regioselective [4+2]-cycloaddition of 3-azatrienes with pyrrolidinocycloalkanone affords bicyclic dihydropyridines and pyridines in a regioselective fashion. 2-Heterodiene moiety of azatriene is involved in the formation of the six-membered ring skeleton of pyridine derivatives. (c) 2006 Elsevier Ltd. All rights reserved.