designed synthetic approach also lies in the use of N-allenamides as substrates, which, after the addition of the first electrophilic radical, preserve a further reactive π-system, making possible the addition of a second α-keto radical and enabling the installation of a keto functionality at a remote position. The good yields, the broad scope, and the possibility to further synthetically elaborate
condensation of carbanions of α-chloro-α-lithiated phosphonates with carbonyl precursors gives direct access to α-chlorine-β-carbonyl phosphonates. The reactions with ethylformate, dimethylformamide, carboxylic esters, diethyl carbonates, diethyl oxalates etc. are discussed. In each case the intermediates have been identified.
Synthesis of α-Hetero Atom Substituted β-Keto and Enamine Phosphonates
作者:Kilsung Lee、Dong Young Oh
DOI:10.1080/00397919108020822
日期:1991.1
Abstract Various α-hetero atom substituted β-keto and enamine phosphonates are prepared by the nucleophilic addition of α-lithioanion of diethyl methylphosphonate to nitriles followed by subsequent addition of electrophiles.
Enantioselective fluorination of α-chloro-β-keto phosphonates in the presence of chiral palladium complexes
作者:Saet Byeol Woo、Chang Won Suh、Kwang Oh Koh、Dae Young Kim
DOI:10.1016/j.tetlet.2013.04.054
日期:2013.6
The catalyticenantioselective electrophilic fluorination of α-chloro-β-keto phosphonates promoted by chiral palladium complexes has been developed, allowing facile synthesis of the corresponding α-chloro-α-fluoro-β-keto phosphonates with excellent enantioselectivity (up to 95% ee).
The dynamic kinetic resolution (DKR) of racemic alpha-chloro beta-ketoesters and alpha-chloro beta-ketophosphonates through ruthenium-mediated asymmetric hydrogenation is reported. The corresponding alpha-chloro beta-hydroxyesters and alpha-chloro beta-hydroxyphosphonates were obtained in good to high enantio- and diastereomeric excesses using, in particular, the atropisomeric ligand DIFLUORPHOS. This methodology allowed an efficient preparation of the anti phenylisoserine side chain of Taxotere (R) which has been used for the hemisynthesis of the cancer therapeutic agent itself. In addition, C-13 NMR in chiral oriented solvents was used to investigate the DKR effect. (C) 2010 Elsevier Ltd. All rights reserved.