The electron transfer photoreaction of (1R,5R)-(+)-sabinene (1) with 1,4-dicyanobenzene and phenanthrene in acetonitrile/methanol gives rise to various optically active ring opened products. The stereochemical relationship between 1 and the products requires that the key intermediate retain the three-dimensional integrity of 1. The results are rationalized via a radical cation, 1a(.+), in which a significant degree of bonding between C-1 and C-5 has been maintained; a ring-opened radical cation, in which C-1 would be planar, is clearly eliminated. 1a(.+) reacts primarily by nucleophilic capture of methanol at the quaternary carbon, generating radical Ain regiospecific and stereoselective fashion. In addition, a hydride shift from C-6 to C-1 produces the beta-phellandrene radical cation 10(.+), which is in turn captured by the nucleophile, also with a high degree of regioselectivity.