Boron trifluoride etherate → (alphaR,betaR)-N-benzyloxycarbonyl-5-chloro-1-ethyl-beta-methyltryptophan methyl ester

Participants

Reaction Steps

To a solution of 5-chloro-1-ethylindole (6.17 g) and methyl (2R,3R)-N-benzyloxycarbonyl-3-methyl-2-aziridinecarboxylate (9.87 g) in dry methylene chloride (100 ml) which was cooled on an ice bath, was added boron trifluoride etherate (4 ml). The mixture was stirred for five minutes and washed with saturated sodium bicarbonate solution, treated with active charcoal, and dried over magnesium sulfate. After removal of the solvent, the crude residue was chromatographed on silica gel (100 g) (toluene as eluent) to give (αR,βR)-N-benzyloxycarbonyl-5-chloro-1-ethyl-β-methyltryptophan methyl ester (4.17 g) as an oil.

Provenance & Evidence