Designing the “Search Pathway” in the Development of a New Class of Highly Efficient Stereoselective Hydrosilylation Catalysts
作者:Vincent César、Stéphane Bellemin-Laponnaz、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/chem.200500132
日期:2005.4.22
coupling of oxazolines and N-heterocyclic carbenes leads to chelating C,N ancillary ligands for asymmetric catalysis that combine both an "anchor" unit and a stereodirecting element. Reacting various N-substituted imidazoles with 2-bromo-4(S)-tert-butyl- and 2-bromo-4(S)-isopropyloxazoline gave the imidazolium precursors of the stereodirecting ancillary ligands. A library of ten different ligand precursors
ATH reductions of aliphaticketones in water catalyzed by ruthenium coordinated by prolinamide ligands produce alcohols with moderate enantiomeric excesses in most cases. A set of seven aliphaticketones is proposed for a rapid evaluation of the enantioselectivity of catalysts by one-pot multi-substrates reduction. The screening of a library of prolinamides shows that according to the structure of
Enantioselective reduction of prochiral ketones using spiroborate esters as catalysts
作者:Viatcheslav Stepanenko、Melvin De Jesús、Wildeliz Correa、Irisbel Guzmán、Cindybeth Vázquez、Wilanet de la Cruz、Margarita Ortiz-Marciales、Charles L. Barnes
DOI:10.1016/j.tetlet.2007.06.086
日期:2007.8
spiroborate esters derived nonracemic 1,2-aminoalcohols and ethylene glycol are reported as highly effective catalysts for the asymmetric borane reduction of a variety of prochiral ketones with borane-dimethylsulfidecomplex at room temperature. Optically active alcohols were obtained in excellent chemical yields using 0.1 to 10 mol % of catalysts with up to 99% ee.
据报道,衍生自非外消旋 1,2-氨基醇和乙二醇的新型螺硼酸酯是室温下各种前手性酮与硼烷-二甲硫醚络合物的不对称硼烷还原反应的高效催化剂。使用 0.1 至 10 mol% 的催化剂和高达 99% ee 以优异的化学产率获得光学活性醇。
Chiral Imidazo[1,5-<i>a</i>]pyridine–Oxazolines: A Versatile Family of NHC Ligands for the Highly Enantioselective Hydrosilylation of Ketones
作者:Chinna Ayya Swamy P、Andrii Varenikov、Graham de Ruiter
DOI:10.1021/acs.organomet.9b00526
日期:2020.1.27
report the synthesis and application of a versatile class of N-heterocyclic carbene ligands based on an imidazo[1,5-a]pyridine-3-ylidine backbone that is fused to a chiral oxazoline auxiliary. The key step in the synthesis of these ligands involves the installation of the oxazoline functionality via a microwave-assisted condensation of a cyano-azolium salt with a wide variety of 2-amino alcohols. The
Mechanism-Based Enantiodivergence in Manganese Reduction Catalysis: A Chiral Pincer Complex for the Highly Enantioselective Hydroboration of Ketones
作者:Vladislav Vasilenko、Clemens K. Blasius、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/anie.201704184
日期:2017.7.10
A manganese alkyl complex containing a chiralbis(oxazolinyl‐methylidene)isoindoline pincer ligand is a precatalyst for a catalytic system of unprecedented activity and selectivity in the enantioselective hydroboration of ketones, thus producing preparatively useful chiral alcohols in excellent yields with up to greater than 99 % ee. It is applicable for both aryl alkyl and dialkyl ketone reduction
含有手性双(恶唑啉基-亚甲基)异二氢吲哚钳位配体的锰烷基络合物是酮对映选择性氢硼化反应中空前的活性和选择性的催化体系的预催化剂,从而以高达99的高收率生产了制备有用的手性醇。 %ee。它适用于在温和的反应条件下(TOF> 450 h -1在-40°C下)。富含地球的贱金属催化剂在极低的催化剂负载量(低至0.1 mol%)下运行,并且具有很高的官能团耐受性。有证据表明存在两种不同的锰催化氢化物转移机理,并介绍了它们在选择性确定步骤中对映体控制的作用。