Enantioselective catalytic radical decarbonylative azidation and cyanation of aldehydes

Abstract

Empowered by the ubiquity of carbonyl functional groups in organic compounds, decarbonylative functionalization was prevalent in the construction of complex molecules. Under this context, asymmetric decarbonylative functionalization has emerged as an efficient pathway to accessing chiral motifs. However, ablation of enantiomeric control in a conventional 2e transition metal–catalyzed process was notable because of harsh conditions (high temperatures, etc.) that are usually required. To address this challenge and use readily accessible aldehyde directly, we report the asymmetric radical decarbonylative azidation and cyanation. Diverse aldehydes were directly used as alkyl radical precursor, engaging in the subsequent inner-sphere or outer-sphere ligand transfer where functional motifs (CN and N 3 ) could be incorporated in excellent site- and enantioselectivity. Mild conditions, broad scope, excellent regioselectivity (driven by polarity-matching strategy), and enantioselectivity were shown for both transformations. This radical decarbonylative strategy using aldehydes as alkyl radical precursor has offered a powerful reaction manifold in asymmetric radical transformations to construct functional motifs regio- and stereoselectively.

Facile synthesis of alkylphosphonates from 4-alkyl-1,4-dihydropyridines via photoinduced formal deformylative phosphonylation

“…Previous studies mainly rely on the use of stoichiometric hydrogen-atom transfer reagents, which abstract aldehydic hydrogen to afford acyl radicals which convert to alkyl radicals after CO extrusion. 11 However, these reactions often suffer from the contamination of acylated byproducts due to relatively slow decarbonylative processes. Alternatively, as pioneered by Nishibayashi and Molander, 12,13 a more practical, two-step approach was developed, which takes advantage of the convenient synthesis of 4-alkyl-1,4-dihydropyridines (DHPs) from aldehydes.…”