反应详情

Cis-methyl 2-(2,4-difluorobenzyl)-4-(3-oxo-2,3-dihydroisoxazol-5-yl)piperidine-1-carboxylate (1.62 g, 4.6 mmol) was subjected to chiral preparative HPLC (Column: Chiralpak AD (250×20), 5 μm particle size, mobile phase: Heptane/EtOH/FA 90/10/0.2, flow rate 18 mL/min) to yield (2R,4S)-methyl 2-(2,4-difluorobenzyl)-4-(3-oxo-2,3-dihydroisoxazol-5-yl)piperidine-1-carboxylate (799 mg, 49%), Chiral purity 99.9% ee, Optical rotation [α]D20=−4.0 (acetonitrile, c=1) and (2S,4R)-methyl 2-(2,4-difluorobenzyl)-4-(3-oxo-2,3-dihydroisoxazol-5-yl)piperidine-1-carboxylate (734 mg, 45%), Chiral purity 99.5% ee, Optical rotation [α]D20=+4.5 (acetonitrile, c=1).