Regioselective nucleophilic addition of organolithium compounds to 3-(4,4-dimethyloxazolin-2-yl)pyridine

Abstract

The nucleophilic heteroaromatic addition reactions of 3-(4,4-dimethyloxazolin-2-yl)pyridine (8) with organolithium compounds as nucleophilic reagents have been investigated. Strongly nucleophilic reagents have been observed to add preferentially to the γ- rather than the α-position of the pyridine ring. Stable crystalline 4-substituted 3-(4,4-dimethyloxazolin-2-yl)-1,4-dihydropyridine addition products have been isolated in good yields. Further, the dihydropyridines could be oxidized to the corresponding 3,4-disubstituted pyridines by a variety of oxidizing agents. Interesting oxidative dealkylations of the 4-t-butyl-1,4-dihydropyridine (9e) have been observed, and they may account for the anomalous ratio of aromatized products.