C-ALKYLATION OF β-DIKETONES WITH BENZYLPYRIDINIUM SALTS. EVIDENCE FOR CHAIN RADICAL MECHANISMS

Article abstract of DOI:10.1016/S0040-4020(01)87840-6

1-(p-Substituted benzyl)-2,4,6-triphenylpyridinium cations react with β-diketone anions by mechanisms which depend on the para-substituent.The p-methoxybenzyl derivative undergoes S_N1 displacement yielding O- and C-benzylated products.The p-nitrobenzyl compound reacts by a chain radicaloid mechanism and gives high yields of C-p-nitrobenzylated diketones.The parent benzyl compound forms some C- and some O-benzylated products, together with bibenzyl, probably by a radical chain reaction which was suppressed by radical traps.