DDQ-catalyzed oxidative α-allylation of isochromans under aerobic conditions

The allylation of isochromans at the α-position via aerobic DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) catalysis is described. This process involves the DDQ oxidation of various isochromans under mild conditions to generate oxocarbenium intermediates, which are effectively stabilized in equilibration in the presence of acid before undergoing allylation. Molecular oxygen and tert -butyl nitrite are employed as an environmentally benign oxidant and mediator, respectively, in the catalytic cycle. The transformation of an allylated product to biologically active molecules has also been successfully demonstrated. A direct C-H activation of isochromans using a DDQ/TBN/O 2 catalytic system, followed by addition of allylstannane in the presence of methanesulfonic acid, provides various α-allyl substituted isochromans efficiently.