Synthesis of spirooxindoles<i>via</i>formal acetylene insertion into a common palladacycle intermediate
作者:Xavier Abel-Snape、Colton E. Johnson、Bianca Imbriaco、Mark Lautens
DOI:10.1039/d3sc01072d
日期:——
A palladium-catalyzed spirocyclization reaction is reported, which is proposed to arise via insertion of an oxabicycle into a palladacycle, formed from carbocyclization and a C–H functionalization sequence. Mechanistic studies suggest the insertion is diastereoselective and a post-catalytic retro-Diels–Alder step furnishes an alkene, wherein the oxibicycle has served as an acetylene surrogate. Aryl
Samarium(II)-mediated spirocyclization by intramolecularaddition of arylradicals onto an aromatic ring was achieved by the reaction of N-(2-iodophenyl)-N-alkylbenzamides with SmI2 in the presence of HMPA, yielding spirocyclic indolin-2-one derivatives. The ether congeners afford spirocyclic benzofuran derivatives in moderate yields by arylradicaladdition onto a benzene ring without having an electron-withdrawing