Chemical synthesis or modification of saccharides remains a major challenge largely because site-selective reactions on their many similar hydroxyl groups are difficult. The lack of efficient chemical synthetic tools has therefore become a main obstacle to understanding saccharide-related biological processes and developing saccharide-based pharmaceuticals. Here, we disclose a programmable multilayered selectivity-amplification strategy enabled by boronic acids and N-heterocyclic carbene (NHC) catalysts for site-specific acylation of unprotected monoglycosides. The boronic acids provide transient shielding on certain hydroxyl groups (while simultaneously promoting reactions of other hydroxyl units) via dynamic covalent bonds to offer the first sets of selectivity controls. The NHC catalysts provide further layers of control by mediating selective acylation of the unshielded hydroxyl moieties. Multiple activating and deactivating forces can be easily modulated to yield programmable selectivity patterns. Structurally diverse monosaccharides and their analogs can be precisely reacted with different acylating reagents, leading to quick construction of sophisticated saccharide-derived products.

糖类的化学合成或修饰仍然是一个主要挑战，主要是因为在它们许多相似的羟基上的位点选择性反应很困难。因此，缺乏有效的化学合成工具已成为了解糖类相关生物过程和开发糖类药物的主要障碍。在这里，我们公开了一种可编程的多层选择性放大策略，该策略由硼酸和 N-杂环卡宾 (NHC) 催化剂实现，用于对未受保护的单糖苷进行位点特异性酰化。硼酸通过动态共价键对某些羟基提供瞬时屏蔽（同时促进其他羟基单元的反应），以提供第一组选择性控制。NHC 催化剂通过介导非屏蔽羟基部分的选择性酰化提供进一步的控制层。可以轻松调节多个激活和停用力以产生可编程的选择性模式。结构多样的单糖及其类似物可以与不同的酰化试剂精确反应，从而快速构建复杂的糖衍生产品。