In Situ Generated AgII-Catalyzed Selective Oxo-Esterification of Alkyne with Alcohol to α-Ketoester: Photophysical Study
摘要:
An expert and easy one-step catalytic method for the multi O-C coupling of alkyne is developed for the synthesis of valuable alpha-ketoesters and their chiral analogues, in contrast to the generation of esters by a noncatalytic method. The in situ generated powerful Ag-II catalyst from AgOTf is the workhorse in the oxidative grafting of alkyne with PhIO and alcohol. The radical mechanism is confirmed in our controlled experiments and UV-vis study.
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
Highly enantioselective carbonyl reduction with borane catalyzed by chiral spiroborate esters derived from chiral beta-aminoalcohols
申请人:Ortiz-Marciales Margarita
公开号:US20080200672A1
公开(公告)日:2008-08-21
Novel spiroborate esters derived from non-recemic 1,2-amino alcohols were examined as chiral catalyst in the borane reduction of acetophenone and other aromatic ketones at room temperature. The optically active alcohols were obtained in excellent chemical yields and up to 99% ee with less than 10% catalyst.
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。