Simple 4-acetoxy-5,6-dihydropyridinium salts: New synthons for the preparation of functionalized piperidine systems

Abstract

The simple 5,6-dihydropyridinium salt 2 (R 1 = CH 3′ R 2-5 = H) was prepared by reaction of the Δ 2 piperidone 1 (obtained from 3 ; 85% overall yield) with acetyl chloride at −50°C. Reaction of 2 with Grignard reagents gave the C-2 substituted products 6 a-f. Compound 6e was converted in three simple steps to the benzomorphan 12 .