Dichloromethane → N,N'-Bis(1-methylethyl)urea

참여 물질

반응 단계

The reation between 8 benzyl-4-benzyloxycarbonyl-alpha- tritylamino-1-thia-3,8-diazaspiro[4.5 ]decane-2-acetic acid (obtained in 6.2.) and diisopropylcarbodiimide (80 g) can be performed in chloroform (400 ml), dichloromethane or a mixture of nitromethane and chloroform, either at ambient temperature, leaving the mixture to stand for 4 weeks, or at 50° C. for 12 hours. In all cases, the 1,3-diisopropylurea formed is removed by filtration, the solvent and excess reagent are evaporated and the residue is passed through a column of silica gel (60 Merck), using chloroform as eluent. In all cases, benzyl 1°-benzyl-6-tritylamino-spiro[penam-2,4'-piperidine ]-3-carboxylate is obtained, which is crystallized from diethy ether in a yield of 25 to 40%; M.P. 191°-192° C. (recrystallized from acetonitrile).

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