Asymmetric synthesis of N-3 substituted phenoxypropyl piperidine benzimidazol-2-one derivatives, potent and selective NOP agonists

The asymmetric synthesis of the potent selective NOP agonist 2-(3-{1-[3-(5-methoxy-2-methyl-phenoxy)-4-methyl-pentyl]-piperidin-4-yl}-2-oxo-2,3-dihydro-benzimidazol-1-yl)-N-methyl-acetamide and analogues was developed. The key step, chiral reduction of methyl isobutyryl acetate, was achieved using a mild Noyori-type asymmetric hydrogenation.