Diisopropylethylamine → 5-[N-(tert-butyloxycarbonyl)aminomethyl]-3,6-dimethoxy-9,9-dimethoxyxanthene-4-acetic acid (O-benzyl-L-glutamyl)amide

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Reaction Steps

A solution of 0.46 g of 5-[(1-tert-butoxyformamido)-methyl]-3,6-dimethoxy-9,9-dimethylxanthene-4-acetic acid and 0.3 g of O-benzyl-L-glutamine hydrochloride in 10 ml of dimethylformamide was cooled to 0° and treated firstly with 0.45 g of O-benzotriazol-1-yl-N,N,N',N'-tetramethyluronium hexafluorophosphate and then with 0.37 ml of diisopropylethylamine. The solution obtained was warmed to room temperature, stirred for 2 hours and then poured into dilute sodium bicarbonate solution. The separated precipitate was filtered off, washed with water and dried in a vacuum, whereby 0.59 g of 5-[N-(tert-butyloxycarbonyl)aminomethyl]-3,6-dimethoxy-9,9-dimethoxyxanthene-4-acetic acid (O-benzyl-L-glutamyl)amide was obtained; MS: 676 (M+H)+.

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