1,3-dipolar cycloadditions of 2-Ethoxy- and 2-(ethylthio)-1-azetines with nitrile oxides, nitrile ylides and nitrilimines: An unexpected 1,2,4-triazole formation

Autor: Robert Westwood, Alan D. Redhouse, Abdul Bassett N. Luheshi, P. D. Kennewell, Karl Hemming, J. Robin Thompson, Robert K. Smalley
Rok vydání: 1993
Předmět:
Zdroj: Tetrahedron. 49:4383-4408
ISSN: 0040-4020
DOI: 10.1016/s0040-4020(01)85755-0
Popis: 2-Ethoxy- and 2-(ethylthio)-1-azetines readily undergo 1,3-dipolar cycloadditions with nitrile oxides and nitrile ylides to give stable 4,5-bicyclic cycloadducts. With nitrilimines, however, the expected 1,3-dipolar cycloadducts and/or unexpected ring-opened products, namely 1,2,4-triazoles, are formed depending on the nature of the nitrilimine N-substituent. In contrast, the azetines fail to react with nitrile sulphides, azomethine ylides, nitrones, aryl azides, and various dienes. X-ray crystallographic data on the nitrile oxide, nitrile ylide, and nitrilimine cycloadducts, and on the 1,2,4-triazoles, are presented. Also a mechanistic rationale for triazole formation is offered.
Databáze: OpenAIRE