Azoles/amides as H sources for direct hydroreduction of sp-C to sp³-C by photocatalysis in air

The reductive hydrofunctionalization of alkynes represents one of the most straightforward strategies for constructing highly functionalized and complex molecular architectures. Current methods typically rely on the use of strongly reductive silanes or boranes as hydrogen sources through metal catalysts under harsh reaction conditions. Herein, we report an efficient photocatalytic strategy for the direct hydroreduction of terminal alkynes from sp-C to sp³-C utilizing readily available azoles or amides as hydrogen sources in air at room temperature. This unprecedented reaction proceeds via a ternary electron donor–acceptor (EDA) complex of sulfinate salts, alkynes, and azoles/amides under visible-light irradiation. This process enables the highly efficient synthesis of α-sulfonyl-β-azole/amino alkanes with high Markovnikov selectivity, excellent N²-regioselectivity, and broad functional group tolerance. A wide range of azoles and amides, including triazoles, imidazoles, tetrazoles, purines, aryl amides, phthalimides, and uracil, serve as effective hydrogen donors under mild conditions. Mechanistic studies using UV-Vis spectroscopy, NMR analysis, and isotopic labeling confirm the formation of a ternary EDA complex and the role of azoles/amides as hydrogen sources. This developed method provides a mild, air-tolerant, versatile and sustainable route to pharmacologically relevant sulfonyl- and amide-containing alkanes from alkynes under ambient conditions using easily accessible hydrogen sources.