(E)- and (Z)-stereodefined enol phosphonates derived from β-ketoesters: stereocomplementary synthesis of fully-substituted α,β-unsaturated esters
作者:Hidefumi Nakatsuji、Yuichiro Ashida、Hiroshi Hori、Yuka Sato、Atsushi Honda、Mayu Taira、Yoo Tanabe
DOI:10.1039/c5ob01097g
日期:——
robust, and stereocomplementary synthesis of fully-substituted (E)- and (Z)-stereodefined α,β-unsaturated esters 3 from accessible α-substituted β-ketoesters 1via (E)- and (Z)-enol phosphonates was achieved. The present method involves two accessible reaction sequences: (i) (E)- and (Z)-stereocomplementary enol phosphorylations of a wide variety of β-ketoesters 1 (24 examples; 71–99% yield, each >95 : 5
通过(E)-和(Z)-烯醇膦酸酯从可及的α-取代的β-酮酸酯1广泛合成,稳固和立体互补地合成完全取代的(E)-和(Z)-立体定义的α,β-不饱和酯3已实现。本方法涉及两个可及的反应序列:(i)多种β-酮酸酯1的(E)-和(Z)-立体互补烯醇磷酸化(24个实例; 71-99%产率,每个> 95:5 ds) ,以及(ii)(E)-和(Z)-使用S型(S)的Suzuki-Miyaura固相交联(16例; 71-91%收率,> 81/19 ds)和Negishi交联(32例; 65-96%收率,> 95:5 ds)使用(E) -和(Z)-烯醇膦酸酯2。描述了关键的反应性N-磷铵(咪唑鎓)中间体I的1 H-NMR监测及其在(E)-和(Z)-他莫昔芬前体6的合成中的应用。