Pyryliumolates II—generation of and cycloaddition reactions with isoxazole annulated pyryliumolates

Abstract

Isoxazole annulated pyryliumolates (formed in situ from diazo compounds 3 and 6) can be trapped with DMAD to form 1:1 adducts (5,8) and in minor amount 2:1 adducts (Schemes 4 and 5). Suitably substituted pyryliumolates (7b,c) undergo an intramolecular cycloaddition giving 9 and 10. Compound 10 can be transformed easily to an annulated tropolone (11). Computational studies on 2:1 adducts and on 11 are reported.