Phosphonate Modification for a Highly (Z)-Selective Synthesis of Unsaturated Esters by Horner-Wadsworth-Emmons Olefination
作者:Fran�ois P. Touchard
DOI:10.1002/ejoc.200400769
日期:2005.5
The Horner–Wadsworth–Emmons (HWE) reaction of various ethyl diarylphosphonoacetates with benzaldehyde, cyclohexane carboxaldehyde and octanal is reported. Selectivities of up to 98 % at –78 °C are obtained with the three substrates. Among all the phosphonates prepared, the reagent based on 2-tert-butylphenol proved to be especially efficient, with Z/E ratios close to 95:5 at 0 °C. It appears thus to
报道了各种二芳基膦酰基乙酸乙酯与苯甲醛、环己烷甲醛和辛醛的 Horner-Wadsworth-Emmons (HWE) 反应。三种底物在 –78 °C 下的选择性高达 98%。在制备的所有膦酸酯中,基于 2-叔丁基苯酚的试剂被证明特别有效,在 0 °C 下 Z/E 比接近 95:5。因此,它似乎是与芳香族和脂肪族醛进行 (Z) 选择性 HWE 反应的首选试剂。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)