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, KOtBu-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.

Development of C2-Symmetric Chiral Spirocyclic Phase-Transfer Catalysts: Synthesis and Application to Asymmetric Alkylation of Glycinate Schiff Base.

A class of C2-symmetric chiral spirocyclic phase-transfer catalysts based on tetramethyl-1,1'-spirobiindane scaffold was synthesized from commercially available bisphenol A in 12 steps with 22-25% total yields, which features a more rigid and stable backbone and smaller dihedral angles and can be easily modified. These catalysts show high catalytic performance in the asymmetric alkylation of tert-butyl glycinate Schiff base at only 2 mol % catalyst loading, giving the target products with up to 92% yield and 98% ee.