Palladium catalyzed synthesis of mandelate derivatives from arylboronic acids and glyoxylate hemiacetals

Direct Aerobic α-Hydroxylation of Arylacetates for the Synthesis of Mandelates

Aerobic α-hydroxylation of α-methylene esters has proven challenging due to overoxidation and hydrolysis of the materials. In this article, KO^tBu-promoted TBAB-catalyzed α-hydroxylation of α-methylene aryl esters using O₂ as the oxygen source has been developed. Both low reaction temperature and catalyst TBAB are keys to success. This reaction provides an environmentally friendly and low-cost approach to mandelates, which are valuable building blocks and widely present in pharmaceuticals.

Pd-catalyzed synthesis of 1-(hetero)aryl-2,2,2-trichloroethanols using chloral hydrate and (hetero)arylboroxines

1-(Hetero)aryl-2,2,2-trichloroethanols are useful key intermediates for the synthesis of various bioactive compounds. Herein, we describe N-heterocyclic carbene (NHC)-coordinated cyclometallated palladium complex (CYP)-catalyzed (hetero)aryl addition of chloral hydrate using (hetero)arylboroxines, providing a new approach to 1-(hetero)aryl-2,2,2-trichloroethanols. Notably, PhS-IPent-CYP which coordinated the bulky yet flexible 2,6-di(pentan-3-yl)aniline (IPent)-based NHC showed good catalytic activities and promoted the transformation in 24-97% yields.