Aldoxime → (5R)-(9H-fluoren-9-yl)methyl 5-((benzyloxy)(tert-butoxycarbonyl)amino)-3-(((tert-butyldimethylsilyl)oxy)methyl)-2-carbamoyl-5,6-dihydropyridine-1(2H)-carboxylate

Participants

Reaction Conditions

Reaction Steps

A mixture of (5R)-(9H-fluoren-9-yl)methyl 5-((benzyloxy)(tert-butoxycarbonyl)amino)-3-(((tert-butyldimethylsilyl)oxy)methyl)-2-cyano-5,6-dihydropyridine-1(2H)-carboxylate (Intermediate 160, 1.3 g, 1.87 mmol), acetaldehyde oxime (0.569 mL, 9.34 mmol) and newly activated copper(II) chloride on 4 Å MS (187 mg, 0.15 mmol) (used 100 mg CuCl2/mol sieves per 1 mmol substrate) in MeOH (5 mL) was stirred under nitrogen at 65° C. for 6 h. The mixture was filtered and evaporated. The residue was purified on silica gel column (0-60%, EtOAc/hexanes). The two diastereomers were combined together to afford the title compound (1.190 g, 89%) as a pale yellow foamy solid.

Provenance & Evidence