Dipolar cycloaddtions of several mesoionic compounds with tert-butylfulvene derivatives; versatile reactions, sterically controlled [4π+ 6π] cycloadditions and a new route to heterocycles isoelectronic with azulene

Abstract

Several mesoionic compounds react with 2-tert-butylfulvene derivatives to form [4π+ 2π] and [4π+ 6π] cycloadducts, which under the reaction conditions, undergo further fragmentation, elimination, or isomerization giving a variety of products including several condensed heterocycles which are isoelectronic with azulene.