Solvent-free melts of unprotected d-ribose and urea generated mainly C1- substituted ribosyl products. The remarkable resolving power of a graphitised-carbon HPLC column allowed products of the reaction formed over a range of heating times and temperatures to be monitored. Heating an uncatalysed mixture of d-ribose and urea at temperatures between 75 °C and 90 °C resulted in complex mixtures of compounds; after 19 h heating at 90 °C, up to ten components could be resolved. At shorter heating times and lower temperatures, the composition and distribution of products varied. By manipulation of the reaction time and temperature, and with the addition of an acid catalyst, it was possible to optimise the yields of selected products. Thus, the acid-catalysed reaction after 1-2 h at 80 °C gave optimal yields of α- and β-d-ribopyranosyl urea, whereas the uncatalysed reaction after 22 h at 75-78 °C in addition produced significant amounts of α-d-ribofuranosyl-1,2- cyclic carbamate [glyco-1,2-oxazolidin-2-one] plus the α- and β-ribofuranosyl ureas. The five compounds were isolated and characterised, demonstrating the significant advantages of this approach; its simplicity, and the ability to produce multiple compounds of biological interest in a single step. LC/MS was used to identify tentatively several other components of the reaction mixture. The unprotected title compounds were prepared, isolated and characterised with water as the only solvent.

中文翻译：

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在碳水化合物熔体中直接形成和分离未保护的α-和β-d-核糖吡喃糖基尿素，α-和β-d-核呋喃糖基尿素以及核糖基1,2-环氨基甲酸酯。

未保护的d-核糖和尿素的无溶剂熔体主要生成C1取代的核糖基产物。石墨化碳HPLC色谱柱的出色分离能力可监控在一定加热时间和温度范围内形成的反应产物。在75°C至90°C的温度下加热未催化的D-核糖和尿素混合物，会形成复杂的化合物混合物；在90°C加热19 h后，最多可以分离10个组分。在较短的加热时间和较低的温度下，产品的组成和分布会发生变化。通过控制反应时间和温度，并添加酸催化剂，可以优化所选产品的收率。因此，在80°C 1-2小时后，酸催化的反应可得到最佳产率的α-和β-d-核糖吡喃糖基脲，而在75-78°C下22 h后未催化的反应另外产生了大量的α-d-呋喃呋喃糖基-1,2-环氨基甲酸酯[glyco-1,2-恶唑烷-2-2-1]以及α-和β -核呋喃糖基脲。分离并鉴定了这五种化合物，证明了这种方法的显着优势。它的简单性以及在一个步骤中即可生产出多种具有生物学意义的化合物的能力。LC / MS用于初步确定反应混合物中的其他几种成分。制备，分离未保护的标题化合物，并用水作为唯一溶剂进行表征。分离并鉴定了这五种化合物，证明了这种方法的显着优势。它的简单性以及在一个步骤中即可生产出多种具有生物学意义的化合物的能力。LC / MS用于初步确定反应混合物中的其他几种成分。制备，分离未保护的标题化合物，并用水作为唯一溶剂进行表征。分离并表征了这五种化合物，证明了该方法的显着优势。它的简单性以及在一个步骤中即可生产出多种具有生物学意义的化合物的能力。LC / MS用于初步确定反应混合物中的其他几种成分。制备，分离未保护的标题化合物，并用水作为唯一溶剂进行表征。