Z- and E-selective Horner–Wadsworth–Emmons reactions
摘要:
In the present work, we determined and evaluated the stereochemical outcome of the Horner-Wadsworth-Emmons (HWE) reaction of 2-oxoalkylphosphonates with different ester functions (bis(2,2,2-trifluoroethyl), 2,2,2-trifluoroethyl methyl, dimethyl) and side chains (aliphatic, aromatic) with three different aldehydes (benzaldehyde, THP- and PPB-protected Corey aldehydes) under two reaction conditions. The trans protocol is generally used in the E-selective HWE reactions, while cis protocol promotes the Z-selectivity.[GRAPHICS].
The preparation of bis(2,2,2-trifluoroethyl) 2-oxoalkylphosphonates by the acylation of bis(2,2,2-trifluoroethyl) methylphosphonate was re-investigated using esters rather than the sensitive acyl chlorides. Based on our optimization, the best results were achieved when the base (LiHMDS) was added to a solution of the phosphonate and the acylating agent at 90 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.
The invention refers to conjugated secondary alkatrienol derivatives, a method of their production and to flavour and perfume compositions comprising them.