Synthesis of polycyclic molecules via cascade radical carbocyclizations of dienynes: the first SnPh3 radical-mediated [2 + 2 + 2] formal cycloaddition of dodeca-1,6-dien-11-ynes

The dodeca-1,6-dien-11-ynes 1 and 5 give the polycyclic molecules 4 and 7, respectively, in the first known [2 + 2 + 2] cycloaddition reaction promoted by triphenyltin hydride, in a cascade free radical process.