Metal-Free Selective Reduction of Acid Chlorides to Aldehydes using 1-Hydrosilatrane

Aldehydes are versatile intermediates in organic chemistry that can be prepared by the selective reduction of readily available or easily prepared carboxylic acid derivatives such as acid chlorides. This transformation is challenging due the reactivity of the aldehyde formed, which under common reduction conditions, is reduced further to the alcohol. Given the utility of aldehydes, a chemoselective method for the preparation of aldehydes from acid chlorides is highly desirable. This work uses 1-hydrosilatrane, an accessible, easy-to-handle reducing agent to selectively reduce acid chlorides to aldehydes. This metal-free method proceeds rapidly at ambient temperature in the presence of an additive N-methylpyrrolidine, producing aldehyde in up to 54% yield with the balance largely remaining as starting material. Over-reduction is not observed. Several experiments are designed to probe at reasons for the incomplete conversion.