Z-Substituted 1,2_dihydropyridines including an optically active one were regioselectively prepared from Z-substituted piperidines through three intermediates, that is, (a) 1,2,3,4_tetrahydropyridines, (b) 5-bromo-6_methoxypiperidines, and (c) 1,2,3,6-tetrahydro-6-methoxypyridines. Since 1-acyl-1,2_dihydropyridines have been known to be useful synthetic intermediates as exemplified by their Diels-Alder type reaction to form nitrogen-heterocycles,' a variety of methods have been reported for synthesis of these dienes. 3 Although the reported syntheses known to be useful ones have been carried out by reduction of pyridinium salts4 or by addition of organometallic reagents to pyridinium salts,5 these methods form both 1,2-and 1,4-dihydropyridines. Thus, convenient methods for the selective synthesis of 1,2_dihydropyridines, especially those possessing substituents at certain positions of pyridine nucleus are quite few so far.6 We report herein a new facile method for the regioselective synthesis of 2-substituted l-(methoxycarbonyl)-1,2_dihydropyridines 5 from piperidines 1. Scheme 1 shows our method which comprises (a) preparation of tetrahydropyridines 2 from I, (b) bromomethoxylation of 2, (c) dehydrobromination of 2 to tetrahydromethoxypyridines 4, and (d) elimination of methanol from 2 affording 5.