Photocycloaddition of Methylcyclobutene and (-)-Piperitone: Synthesis of (-)-Shyobunone and Related Sesquiterpenes
Photocycloaddition of methylcyclobutene to (-)-piperitone affords the photoadduct 3a.Flash vacuum pyrolysis of the photoadduct 3a affords (-)-shyobunone (4a), 2-epi-(-)-shyobunone (5a), 3-epi-(-)-shybunone(6a),2,3-diepi-(-)-shyobunone (7a), and (R)-(+)-is