1,3-Dipolar Cycloadditions of 4-Acetoxy Allenoates: Access to 2,3-Dihydropyrazoles, 2,3-Dihydroisoxazoles, and Indolizines

Org Lett. 2015 Nov 6;17(21):5376-9. doi: 10.1021/acs.orglett.5b02724. Epub 2015 Oct 15.

Abstract

The thermal 1,3-dipolar cycloadditions of 4-acetoxyallenoates 1 with various dipoles have been reported. When azomethine imines and nitrones are used as the 1,3-dipole partner, the corresponding reactions afford 2,3-dihydropyrazole and 2,3-dihydroisoxazole derivatives, respectively. These reactions might proceed via a thermal 1,3-dipolar cycloaddition and the subsequent elimination of HOAc. In addition, allenoates 1 react well with in situ generated azomethine ylides in which a similar cycloaddition pathway is followed by oxidative aromatization to give indolizine derivatives.

Publication types

  • Research Support, Non-U.S. Gov't