methyl (4S)-4-{[(tert-butoxy)carbonyl]amino}cyclopent-1-ene-1-carboxylate → ST50825900

Participants

Reaction Steps

((1,2-Bis(2R,5R)-2,5-dimethylphospholano)ethane)(cyclooctadiene)rhodium(I) trifluoromethanesulfonate (179 mg, 0.1 mol %) was added to a degassed solution of (4S)-4-tert-butoxycarbonylaminocyclopent-1-enecarboxylic acid methyl ester (70 g, 0.29 mol) in methanol (350 ml). The reaction mixture was transferred to a bomb and after purging with nitrogen and then hydrogen, a hydrogen pressure of 5 bar was applied and the reaction stirred for 62 h. The pressure was released and the bomb purged with nitrogen. Concentration of the reaction mixture gave a residue which was redissolved in dichloromethane (300 ml). Addition of silica (20 g) with stirring removed the catalyst from the reaction and filtration and concentration of the organic solution gave crude product as a yellow oil that solidified on standing (92% d.e.; measured by gc analysis). Crystallisation from tert-butylmethylether and heptane gave the title compound as colourless needles of 97% d.e. (63 g, 89%).

Provenance & Evidence