Synthesis of 1-arylcycloprop-2-ene carboxylates with non-substituted double bond via a Rh(II)-catalyzed cyclopropenation of trimethylsilylacetylene with coarsely purified aryldiazoacetates

A new synthetic protocol for the preparation of 3-aryl-3-methoxycarbonyl cyclopropenes with an unsubstituted double bond has been developed that allowed for expanded substrate scope and improved product yields. The method involves Rh(II)-catalyzed transfer of carbenoids generated from unpurified aryldiazoesters, followed by desilylation, and is compatible with a wide range of aryldiazoesters. The employed continuous extraction of hardly soluble crude diazoesters helps avoid laborious and often cost-prohibitive isolation and purification of sensitive diazoester precursors.