Enantioselective preparation of sec. Alcohols from aldehydes and dialkyl zinc compounds, generated in situ from Grignard reagents, using substoichiometric amounts of TADDOL-titanates
作者:Joanna Linda von dem Bussche-Hünnefeld、Dieter Seebach
DOI:10.1016/0040-4020(92)80023-9
日期:1992.7
the Schlenk trick (precipitation of MgX2 from ethereal solutions by the addition of 1,4-dioxane) mixtures of a Grignard reagent RMgX (X = Cl, Br, I) and 0.5 equiv. ZnCl2 in Et2O can be converted to zinc alkyls R2Zn which in turn are added with enantio-selectivities of up to 99 : 1 to aliphatic and aromatic aldehydes in the presence of Ti(OCHMe2)4 and a chiral titanate derived from an α,α,α′,α′-tetraaryl-1
使用Schlenk技巧(通过添加1,4-二恶烷,从醚溶液中沉淀出MgX 2),将格氏试剂RMgX(X = Cl,Br,I)和0.5当量的混合物。可以将Et 2 O中的ZnCl 2转化为烷基锌R 2 Zn,然后在Ti(OCHMe 2)4和手性钛酸酯的存在下,将脂族和芳族醛的对映选择性高达99:1。由α,α,α',α'-四芳基-1,3-二氧戊环-4,5-二甲醇(TADDOL)制得。格氏试剂盒也可以使用双键,苯环或缩醛基。比较了不同的TADDOL在这类对映选择性反应中的用途。