Differentially protected galactosamine building blocks are key components for the synthesis of human and bacterial oligosaccharides. The azidophenylselenylation of 3,4,6-tri-O-acetyl-d-galactal provides straightforward access to the corresponding 2-nitrogenated glycoside. Poor reproducibility and the use of azides that lead to the formation of potentially explosive and toxic species limit the scalability of this reaction and render it a bottleneck for carbohydrate synthesis. Here, we present a method for the safe, efficient, and reliable azidophenylselenylation of 3,4,6-tri-O-acetyl-d-galactal at room temperature, using continuous flow chemistry. Careful analysis of the transformation resulted in reaction conditions that produce minimal side products while the reaction time was reduced drastically when compared to batch reactions. The flow setup is readily scalable to process 5 mmol of galactal in 3 h, producing 1.2 mmol/h of product.

中文翻译：

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安全且可扩展的半乳糖连续流动叠氮基苯硒基化反应，以制备半乳糖胺结构单元

差异保护的半乳糖胺构件是合成人和细菌寡糖的关键成分。的3,4,6-三-的azidophenylselenylation ö乙酰基d -galactal提供直接的访问相应的2-氮化糖苷。可再生性差和叠氮化物的使用导致形成潜在的爆炸性和有毒物质，限制了该反应的可扩展性，并使其成为碳水化合物合成的瓶颈。在这里，我们提出了一种安全，有效和可靠的3,4,6-tri- O-乙酰基-d叠氮基苯硒基化方法-在室温下使用连续流化学法测定半乳糖。与分批反应相比，对转化的仔细分析导致反应条件产生的副产物最少，而反应时间却大大减少。流量设置易于扩展，可在3小时内处理5 mmol半乳糖，产生1.2 mmol / h的产物。