The photophysical and photochemical behavior of a series of α-[(N-methylamino)alkyl]styrenes with two to four methylenes separating the styryl and amino groups and an (aminoalkyl) indene have been investigated and the results compared to those for the intermolecular reaction of α-methylstyrene with diethylamine. Both inter- and intramolecular quenching of styrene fluorescence by the amine is observed, indicative of electron-transfer quenching as the initial step in these reactions. The resulting exciplex undergoes regioselective N-H proton transfer to styrene C-β yielding a biradical, in the case of the intramolecular reaction, and a radical pair, in the case of the intermolecular reaction. Biradical or radical pair combination yields styrene-amine addition products. The conformation of the intermediate exciplex is proposed to control the regioselectivity of the intramolecular N-H proton transfer process.
ASJC Scopus subject areas
- Organic Chemistry