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 deprotonation of an aminium radical intermediate by the stilbene radical anion. Selective oxidation results from a stereoelectronic effect which is most evident when one or more alkyl group is highly branched.
ASJC Scopus subject areas
- Organic Chemistry