The reactivity of carbonyl functional groups largely depends on the substituents on the carbon atom. Reversal of the commonly accepted order of reactivity of different carbonyl compounds requires novel synthetic approaches. Achieving selective reduction will enable the transformation of carbon resources such as plastic waste, carbon dioxide and biomass into valuable chemicals. In this Review, we explore the reduction of less reactive carbonyl groups in the presence of those typically considered more reactive. We discuss reductions, including the controlled reduction of ureas, amides and esters to aldehydes, as well as chemoselective reductions of carbonyl groups, including the reduction of ureas over carbamates, amides and esters; the reduction of amides over esters, ketones and aldehydes; and the reduction of ketones over aldehydes.

羰基官能团的反应性很大程度上取决于碳原子上的取代基。逆转不同羰基化合物普遍接受的反应顺序需要新的合成方法。实现选择性减排将使塑料废物、二氧化碳和生物质等碳资源转化为有价值的化学品。在这篇综述中，我们探索了在通常被认为更具反应性的羰基存在下还原反应性较低的羰基。我们讨论还原，包括脲、酰胺和酯向醛的受控还原，以及羰基的化学选择性还原，包括脲相对于氨基甲酸酯、酰胺和酯的还原；酰胺相对于酯、酮和醛的还原；以及酮相对于醛的还原。