A concise synthesis of (5R,6S)-tert-butyl 5-acetoxy-6-(hydroxymethyl)-5,6-dihydropyridine-1(2H)-carboxylate

An efficient synthesis of (5 R,6 S)-tert -butyl 5-acetoxy-6-(hydroxymethyl)-5,6-dihydropyridine- 1(2 H)-carboxylate 1, a common intermediate for various polyhydroxylated piperidines is reported in six steps with 32% overall yield starti ng from Garner's aldehyde. The key steps include the diastereoselective nucleophilic additio n and intramolecular cyclization. (5 R,6 S)-tert - butyl 5-acetoxy-6-(hydroxymethyl)-5,6-dihydropyridine-1(2 H)-carboxylate is a common precursor for the synthesis of 1-deoxy- L-mannojirimycin, 1-deoxy-L-idonojirimycin, L- fagomycin and related analogues.