反应详情

A solution of 3 g (6.55 mmol) of 5-[(1-tert-butoxyformamido)methyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetic acid in 65 ml of methylene chloride was cooled to 20° and treated with 1.1 ml (10.62 mmol) of benzyl alcohol. After the addition of 20 mg of 4-dimethylaminopyridine a solution of 1.5 g (7.27 mmol) of dicyclohexylcarbodiimide in 16 ml of methylene chloride was added dropwise, whereupon the mixture was warmed to room temperature and was stirred for 3 hours. The precipitated dicyclohexylurea was filtered off and washed with a small amount of methylene chloride. The filtrate was washed with sodium bicarbonate solution and water, dried over sodium sulphate and concentrated. The residue remaining was chromatographed on silica gel with hexane/ethyl acetate, whereby 2.9 g of benzyl 5-[(1-tert-butoxyformamido)methyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate were obtained as a colourless powder m.p. of 139°-141°; IR 3443, 2972, 2930, 1724, 1605, 1498 cm-1.

1. additionwas added dropwise, whereupon the mixture
2. filtrationThe precipitated dicyclohexylurea was filtered off
3. washwashed with a small amount of methylene chloride
4. washThe filtrate was washed with sodium bicarbonate solution and water
5. dry with materialdried over sodium sulphate
6. concentrationconcentrated
7. customThe residue remaining was chromatographed on silica gel with hexane/ethyl acetate