Catalytic Enantioselective Hydrosilylation of Aromatic Ketones Using Rhodium Complexes of TADDOL-Derived Cyclic Phosphonites and Phosphites
作者:Jun-ichi Sakaki、W. Bernd Schweizer、Dieter Seebach
DOI:10.1002/hlca.19930760722
日期:1993.11.3
phosphites 2–4 are readily available from Cl2PR and (R,R)- or (S,S)-α,α,α′,α′-tetraaryl-1,3-dioxolane-4,5-dimethanols (= TADDOLs 1, which, in turn, are only two steps away from tartrate); the X-ray crystal structure of one representative, the phenyl phosphonite 2b, was determined. Five previously described and six new ones of the chiral P derivatives were tested as ligands for RhI- and PdO-catalyzed reactions
环状亚膦酸酯和亚磷酸酯2-4可从Cl 2 PR和(R,R)-或(S,S)-α,α,α',α'-四芳基-1,3-二氧戊环-4,5-获得。二甲醇(= TADDOLs 1,距酒石酸只有两步之遥);测定了代表性的苯基亚膦酸酯2b的X射线晶体结构。测试了五种先前描述的手性P衍生物和六种新的手性P衍生物作为Rh I-和Pd O的配体-催化的反应,例如CC键的加氢基化,加氢硼化和加氢甲硅烷基化;尽管所得催化剂具有高活性和区域选择性,但它们并未导致产物中有用的对映异构体富集(方案1)。相反,在去甲硅烷基化后,通过Ph 2 SiH 2(1.2当量)对苯基和2-萘甲基或乙基酮进行硅氢加成,可得到相应的(R)-构型仲醇,在0.1存在下具有最高87%ee当量 五(2-萘基)取代的亚膦酸酯3d和0.02摩尔当量。Rh(表1)。