Dedioxygenative Phosphonylation of Carboxylic Acids.

Dedioxygenative transformations of carboxylic acids are faced with the significant challenges in efficiently breaking multiple C-O bonds and achieving broad applicability across diverse carboxylic acids, thereby hampering the development and application of this field. In this work, through the cooperation of multiple catalysts, we realized a dedioxygenative phosphonylation of carboxylic acids that is applicable to both aliphatic and aromatic substrates, showing good scope and functional-group tolerance. This protocol also demonstrates promising performance in the late-stage modification of complex molecules. Meanwhile, it establishes a formal deoxygenative coupling approach that enables rapid access to alkenes from carboxylic acids and aldehydes or alcohols. Mechanistic studies reveal distinct activation modes for different C-O bonds and further highlight a carbon-retentive transformation pattern of carboxylic acids, complementing conventional carbon-deletion decarboxylative phosphonylation based on redox-active esters or other strategies.