Enantio‐, Diastereo‐ and Regioselective Synthesis of Chiral Cyclic and Acyclic
<i>gem</i>
‐Difluoromethylenes by Palladium‐Catalyzed [4+2] Cycloaddition
A Pd-catalyzed asymmetric [4+2] cycloaddition between substituted-2-alkylidenetrimethylene carbonates and cyclic or acyclic gem-difluoroalkyl ketones enabled the synthesis of chiral gem-difluoromethylene compounds. A novel phosphoramidite ligand, which contains a bulky 1,1-dinaphthylmethanamino moiety, was the key to providing high yield products with excellent enantio-, diastereo-, and regioselectivity
Various kinds of 3-substituted (Z)-hydroxymethyl-2-propenyl acetates were conveniently obtained in excellent yields by highly regioselective hydrolysis of 2-alkylidene-1,3-propylene diacetates in the presence of 100 w/w % of porcine pancreas lipase (PPL)Type II. (C) 2008 Elsevier Ltd. All rights reserved.