provides polyfunctional phosphines in good yields. Especially attractive is the hydroboration/boron-zinc exchange sequence which allows the conversion of functionalized olefins into polyfunctional phosphines in a one-pot procedure. Several new chiral phosphines have been prepared starting from readily available chiral olefins (terpenes) and their efficiency in asymmetric hydrogenation reactions has been
Dramatic titanium alkoxide effect in the catalytic enantioselective addition of dialkylzincs to aldehydes
作者:Stefan Nowotny、Stephan Vettel、Paul Knochel
DOI:10.1016/s0040-4039(00)60721-9
日期:1994.6
The use of Ti(Ot-Bu)4, or related bulky titanium(IV) alkoxides, as cocatalysts instead of Ti(Oi-Pr)4 in the enantioselective addition of dimethylzinc to aldehydes in the presence of the catalyst 2 (8 mol%) leads to a dramatic improvement of the enantioselectivity (0%ee to 93%ee). The scope and the limitations of this effect are described.
carbonyl group, cyano group) in an alkyl halide facilitates its cross-coupling reaction with various diorganozincs in the presence of Ni(acac)(2) (7.5-10 mol % in THF/NMP mixtures). These results were used to develop a new general cross-coupling reaction between functionalized diorganozincs and alkyliodides using m- or p-trifluoromethylstyrene as a reaction promotor and Ni(acac)(2) as a catalyst (7.5-10
Chiral Allylic Cyanohydrins as Versatile Substrates for Diastereoselective Copper(I)-mediated S<sub>N</sub>2′ Allylic Substitutions
作者:Paul Knochel、Sylvie Perrone、Albrecht Metzger
DOI:10.1055/s-2007-973881
日期:2007.4
2,6-Difluorobenzoated derivatives bearing a protected cyanohydrin function undergo highly stereoselective copper(I)-mediated SN2′ allylicsubstitutionreactions with diorganozinc reagents leading to chiral unsaturated nitriles.
带有受保护的氰醇功能的 2,6-二氟苯甲酸衍生物与二有机锌试剂发生高度立体选择性的铜 (I) 介导的 SN 2' 烯丙基取代反应,产生手性不饱和腈。
Enantioselective synthesis of 1,2-, 1,3- and 1,4- aminoalcohols by the addition of dialkylzincs to 1,2-, 1,3- and 1,4- aminoaldehydes
作者:Christian Lutz、Volker Lutz、Paul Knochel
DOI:10.1016/s0040-4020(98)00297-x
日期:1998.6
aminoalcohols were prepared by the addition of functionalized dialkylzincs to 1,3-aliphatic and 1,4-unsaturated aminoaldehydes with good to excellent enantioselectivity. Syn- or anti-1,2-aminoalcohols are stereoselectively obtained by asymmetric addition of dialkylzincs to α-aminoaldehydes depending on the choice of the chiral catalyst. A chelate controlledaddition is observed if less than stoichiometric
通过向1,3-脂族和1,4-不饱和氨基醛中添加官能化的二烷基锌,制备手性的1,3-和1,4-氨基醇,对映选择性很好。根据手性催化剂的选择,通过不对称地将二烷基锌加成到α-氨基醛上来立体选择性地获得顺-或抗-1,2-氨基醇。如果使用小于化学计量的Ti(O i -Pr)4,则观察到螯合物受控的添加。