Ring Contractions and Expansions of Vicinally Disubstituted Cyclobutanes and Cyclopropylmethyl Compounds

Abstract

Abstract Cyclobutanes and cyclopropylmethyl compounds vicinally disubstituted in appropriate manner by one electron‐donating group and one leaving or electron‐receiving group undergo extremely facile ring contractions and expansions respectively. Unlike many rearrangements of small‐ring compounds and most rearrangements of larger‐ring compounds, these reactions usually give a single product in high yield and thus possess real synthetic interest. The subject matter of this progress report is classified according to the substituents in question since the nature of these groups largely determines the conditions under which rearrangement takes place.