Photochemical synthesis of N-adamantylhomoallylamines through addition of cyclic olefins to imines catalyzed by alumina grafted cadmium sulfide

Abstract

Grafting cadmium sulfide onto alumina induces a small bandgap widening and a more significant lifetime variation of the light generated charge carriers from 0.76 microseconds measured for pristine CdS to 0.75, 0.86, and 1.20 microseconds found for CdS/Al₂O₃ containing 30, 20, and 9% of CdS, respectively. The quasi-Fermi level of electrons of −0.42 V (NHE) is not significantly changed. These alumina grafted semiconductor photocatalysts enable the linear addition of cyclopentene, cyclohexene, and α-pinene to N-adamantylimines affording novel homoallyladamantylamines in isolated yields of 21–85% through a regioselective C–C heterocoupling of intermediate allyl and α-aminobenzyl radicals. As by-products hydrodimers of the imine are formed by C–C homocoupling of the benzylic radicals. Different from heterocoupling, the homocoupling is a stereospecific process directed by the nature of the olefin employed in the reaction.