Organocatalytic selenosulfonylation of the C–C doublebond of α,β-unsaturatedketones to construct two contiguous stereogenic centers in an aqueous medium was described. A series of α-selenyl and β-sulfonyl ketones with various functional groups were synthesized in good yields and enantioselectivities with saturated NaCl solution as the solvent. In addition, this protocol had been successfully scaled
Catalytic asymmetric allylations of achiral and chiral aldehydes via BINOL–Zr complex
作者:Michio Kurosu、Miguel Lorca
DOI:10.1016/s0040-4039(02)00139-9
日期:2002.3
The complex generated from BINOL, Zr(OtBu)4, and 4 Å MS in toluene–pivalonitrile is very effective for catalyticasymmetricallylation of aldehydes using allyltributyltin. The reactions of achiral aldehyde under these conditions are completed within 3 h using 10–20 mol% of the complex at −20°C. The ees of homoallylic alcohols can be enhanced up to 98% via the tandem asymmetric allylation–Oppenauer
由甲苯,新戊腈中的BINOL,Zr(O t Bu)4和4ÅMS生成的络合物对于使用烯丙基三丁基锡催化醛的催化不对称烯丙基化非常有效。在20°C下,使用10–20 mol%的配合物,可在3小时内完成这些条件下的非手性醛的反应。通过串联不对称烯丙基化-Oppenauer氧化可将均丙醇的ee提高至98%。对β-烷氧基醛的这些条件的范围和局限性进行了广泛的研究。
Enantioselective N-Alkylation of Nitroindoles under Phase-Transfer Catalysis
ring was essential to control the stereoselectivity of the reaction. Michael adducts were obtained in high yields and moderate enantioselectivities in the reaction between 4-nitroindole and various Michael acceptors in the presence of cinchona alkaloid based phase-transfer catalysts. In addition to outlining the scope and limitations of the method, the geometries of the transition states of the reaction
Enzyme‐ and Ruthenium‐Catalyzed Enantioselective Transformation of α‐Allenic Alcohols into 2,3‐Dihydrofurans
作者:Bin Yang、Can Zhu、Youai Qiu、Jan‐E. Bäckvall
DOI:10.1002/anie.201601505
日期:2016.4.25
An efficient one‐pot method for the enzyme‐ and ruthenium‐catalyzed enantioselective transformation of α‐allenicalcohols into 2,3‐dihydrofurans has been developed. The method involves an enzymatic kinetic resolution and a subsequent ruthenium‐catalyzed cycloisomerization, which provides 2,3‐dihydrofurans with excellent enantioselectivity (up to >99 % ee). A ruthenium carbene species was proposed as
开发了一种有效的一锅法,用于酶和钌催化的 α-丙二烯醇对映选择性转化为 2,3-二氢呋喃。该方法涉及酶动力学拆分和随后的钌催化环异构化,从而提供具有优异对映选择性的 2,3-二氢呋喃(高达 >99 % ee )。钌卡宾被提议作为环异构化的关键中间体。
Asymmetric Conjugate Addition of Phosphonates to Enones Using Cinchona–Diaminomethylenemalononitrile Organocatalysts
Asymmetricconjugate additions of phosphonates to trans-crotonophenone and chalcone derivatives using a diaminomethylenemalononitrile organocatalyst resulted in the generation of the corresponding chiral γ-ketophosphonates in high yields with excellent enantioselectivities (up to 95% ee). This report is the first successful example of asymmetric 1,4-additions of phosphonate to α,β-unsaturated ketones