Treatment of β-fluoroalkylated-α,β-unsaturated ketones with 1.2 equiv. of various arylboronic acids in the presence of 5 mol% of [Rh(COD)2]BF4 and 6 mol% of (S)-BINAP in toluene/H2O (v/v = 4/1) at the reflux temperature for 3 h gave the corresponding Michael adducts in high yields with over 90% enantioselectivity. Though other electron-deficient alkenes, such as vinylsulfone and vinylphosphonate, were found to be much less reactive in the rhodium-catalyzed conjugate addition with arylboronic acids, the reaction of various arylstannanes toward such electron-deficient alkenes took place very smoothly to afford the corresponding adducts in high yields.
在
甲苯/
H2O(v/v = 4/1)溶液中,加入 5 摩尔的[Rh(COD)2]BF4 和 6 摩尔的(S)-BINAP,在回流温度下,用 1.2 等份的各种芳基
硼酸处理δ-氟烷基化-δ,δ-不饱和酮 3 小时,可得到相应的迈克尔加合物,产率高,对映选择性超过 90%。虽然其他缺电子烯类,如
乙烯基砜和
乙烯基膦酸,在
铑催化的芳基
硼酸共轭加成反应中反应性要差得多,但各种芳基
锡烷与这些缺电子烯类的反应非常顺利,能以高产率得到相应的加合物。