Photochemical Addition of Tertiary Amines to Stilbene. Stereoelectronic Control of Tertiary Amine Oxidation.

Article abstract of DOI:10.1021/jo00319a007

The photochemical addition reactions of seven nonsymmetrical tertiary amines with singlet trans-stilbene are described.Addition of methyldiisopropylamine or isopropyldimethylamine is highly selective for formation of the least substituted α-amino radical, whereas addition of several less highly branched amines is relatively nonselective.The product isotope effect for tert-butylmethyl(trideuteriomethyl)amine is 2.2+/-0.2.Product selectivity is determined by the orientation of the deprotonation of an aminium radical intermediate by the stilbene radical anion.Selectiveoxidation results from e stereoelectronic effect which is most evident w hen one more alkyl group is highly branched.