Dihalogenation/cyclization reactions of bicyclo[1.1.0]butane-1-carboxamide: rapid access to dihalogenated spiro[cyclobutane-1,3'-quinolin]-2'-one derivatives.

A rapid catalyst-free dihalogenation/cyclization reaction of N-(2-(arylethynyl)phenyl)bicycle[1.1.0]butane-1-carboxamides and IX or NXS to assemble dihalogenated spiro[cyclobutane-1,3'-quinolin]-2'-one derivatives via a strain-release reaction has been developed. The reaction features a broad substrate scope, good functional group compatibility, low-cost halogenating reagents, and mild reaction conditions. Moreover, not using any catalysts and an extremely short reaction time (3-5 min) are the most important highlights of this synthesis.