Somsák László, Felföldi Nóra, Kónya Bálint, Hüse Csaba, Telepó Katalin, Bokor Eva, Czifrák Katalin
Department of Organic Chemistry, University of Debrecen, PO Box 20, H-4010 Debrecen, Hungary.
Carbohydr Res. 2008 Aug 11;343(12):2083-93. doi: 10.1016/j.carres.2008.01.045. Epub 2008 Feb 7.
Preparation of O-peracetylated N-beta-d-glucopyranosyl-N'-acyl urea derivatives resulted in the formation of anomeric mixtures under the following conditions: acylation of O-peracetylated beta-d-glucopyranosyl urea by acyl chlorides in the presence of ZnCl(2) in refluxing CHCl(3); addition of O-peracetylated beta-d-glucopyranosylamine to acyl isocyanates in acetonitrile at rt; addition of carboxamides to in situ prepared O-peracetylated beta-d-glucopyranosyl isocyanate in refluxing toluene. Deprotection of O-peracetylated N-beta-d-glucopyranosyl-N'-acyl ureas either under base (NaOMe in MeOH at or below rt) or under acid (KHSO(4) or AcCl in MeOH at rt) catalyzed transesterification conditions resulted in unavoidable partial cleavage of the N'-acyl moieties. Reaction of beta-d-glucopyranosylammonium carbamate with an isocyanate, isothiocyanate or isoselenocyanate in dry pyridine at rt appears as a general method for the preparation of the corresponding beta-d-glucopyranosyl ureas, -thio- and -selenoureas, respectively, inclusive N'-acyl derivatives.
在以下条件下，制备O-过乙酰化的N-β-D-吡喃葡萄糖基-N'-酰基脲衍生物会导致异头物混合物的形成：在回流的CHCl₃中，在ZnCl₂存在下，用酰氯对O-过乙酰化的β-D-吡喃葡萄糖基脲进行酰化；在室温下，于乙腈中将O-过乙酰化的β-D-吡喃葡萄糖胺加入到酰基异氰酸酯中；在回流的甲苯中，将羧酰胺加入到原位制备得到的O-过乙酰化的β-D-吡喃葡萄糖基异氰酸酯中。在碱（在室温或低于室温下，于甲醇中的NaOMe）或酸（在室温下，于甲醇中的KHSO₄或AcCl）催化的酯交换条件下，对O-过乙酰化的N-β-D-吡喃葡萄糖基-N'-酰基脲进行脱保护会导致N'-酰基部分不可避免地发生部分裂解。在室温下，在干燥的吡啶中，使β-D-吡喃葡萄糖基氨基甲酸铵与异氰酸酯、异硫氰酸酯或异硒氰酸酯反应，似乎是分别制备相应的β-D-吡喃葡萄糖基脲、硫脲和硒脲（包括N'-酰基衍生物）的通用方法。
