Identifying a general bench-stable precursor of multifunctional sugar residues that is also amenable to further activation under mild conditions remains a great challenge in carbohydrate chemistry. Here, we show that heteroaryl glycosyl sulfones undergo desulfonylative cross-coupling with electrophiles in the presence of a Hantzsch ester and a weak base under visible light illumination at ambient temperature. Illumination was found to initiate the reactivity of an in situ-generated Hantzsch ester–base complex, triggering single-electron transfer steps that activate sulfones and afford glycosyl radicals, which are readily utilized for a range of stereocontrolled carbon–carbon and carbon–sulfur bond formations. Importantly, the heteroaryl glycosyl sulfones can be synthesized on a multi-gram scale. Furthermore, this catalyst- and transition metal-free approach enables sulfone donors of various monosaccharides and glycans to be transformed to synthetically valuable glycosides with high stereochemical purity and broad functional group tolerance. This method overcomes previous limitations in scope, scalability and donor instability.

鉴定一种通用的、可在温和条件下进一步活化的多功能糖残基前体仍然是碳水化合物化学的一大挑战。在这里，我们展示了杂芳基糖基砜在环境温度下可见光照射下在 Hantzsch 酯和弱碱存在下与亲电试剂发生脱磺基交叉偶联。发现光照引发原位产生的 Hantzsch 酯-碱复合物的反应性，触发单电子转移步骤，激活砜并提供糖基自由基，这些自由基很容易用于一系列立体控制的碳-碳和碳-硫键编队。重要的是，杂芳基糖基砜可以以多克的规模合成。此外，这种不含催化剂和过渡金属的方法使各种单糖和聚糖的砜供体能够转化为具有高立体化学纯度和广泛官能团耐受性的合成有价值的糖苷。这种方法克服了以前在范围、可扩展性和供体不稳定性方面的限制。