Diisopropylethylamine → benzyl 5-[(N-(9-fluorenylmethoxycarbonyl)-4-O-tert-butyl-D-aspartyl)aminomethyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate

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Reaction Steps

A solution of 0.17 g of benzyl 5-aminomethyl-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate trifluoroacetate and 0.14 g of N-(9-fluorenylmethoxycarbonyl)-4-O-tert-butyl-D-aspartic acid in 5 ml of dimethylformamide was treated, with 0.11 g of O-benzotriazol-1-yl-N,N,N',N'-tetramethyluronium tetrafluoroborate and with 0.11 ml of diisopropylethylamine. The mixture was stirred at room temperature for 1 hour and thereafter poured into dilute sodium bicarbonate solution. The resulting precipitate was filtered off, washed with water KHSO4 /K2SO4 solution and again with water and dried with 40° in a vacuum, whereby 0.25 g of benzyl 5-[(N-(9-fluorenylmethoxycarbonyl)-4-O-tert-butyl-D-aspartyl)aminomethyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetate was obtained; MS: 841.5 (M+H)+.

Provenance & Evidence