Sodium Bicarbonate → benzyl 5-[(N-benzyloxycarbonyl-L-alanyl)aminomethyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate

Participants

Reaction Steps

A solution of 0.35 g of benzyl 5-aminomethyl-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate trifluoroacetate in 70 ml of acetonitrite was cooled to 0° and treated with 0.15 g of N-benzyloxycarbonyl-L-alanine. A total of 0.36 9 of O-benzotriazol-1-yl-N,N,N',N'-tetramethyluronium hexafluorophosphate and 0.17 g of sodium bicarbonate were added in several portions. The reaction mixture was stirred for a total of 36 hours and thereby warmed to room temperature, whereupon it was diluted with ice-water and extracted with methylene chloride. The organic phase was washed with water, dried over magnesium sulphate and concentrated. The residue was chromatographed several times over silica gel in chloroform/methanol, whereby 0.33 g of benzyl 5-[(N-benzyloxycarbonyl-L-alanyl)aminomethyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate was obtained as a colourless foam; IR 1728, 1673, 1605, 1494 cm-1.

Provenance & Evidence