RESUMO
A photocatalytic decarboxylative functionalization of cyclopropenes is reported. Starting from a broad range of redox-active ester-substituted cyclopropenes, cyclopropenylphthalimides can be synthesized in the absence of a nucleophile. Alternatively, different carbon and heteroatom nucleophiles can be introduced. The transformation proceeds most probably through the formation of an aromatic cyclopropenium cation, followed by trapping with the nucleophiles.
RESUMO
An electrophile-induced semipinacol rearrangement of cyclopropenylcarbinols is reported. This transformation gives access to various polyfunctionalized cyclopropanes under mild metal-free conditions. The scope of the reaction includes iodine, sulfur and selenium electrophiles, aryl and strained ring migrating groups, and diverse substitution patterns on the cyclopropene. The reaction is particularly efficient for the synthesis of small ring-containing spirocycles, which are important rigid three-dimensional building blocks for medicinal chemistry.
RESUMO
We report the synthesis of quinolines using cyclopropenes and an azidobenziodazolone (ABZ) hypervalent iodine reagent as an azide radical source under visible-light irradiation. Multisubstituted quinoline products were obtained in 34-81% yield. The reaction was most efficient for 3-trifluoromethylcyclopropenes, affording valuable 4-trifluoromethylquinolines. The transformation probably proceeds through the cyclization of an iminyl radical formed by the addition of the azide radical on the cyclopropene double bond, followed by ring-opening and fragmentation.