Palladium-Catalyzed Aerobic Oxidative Kinetic Resolution of Alcohols with an Achiral Exogenous Base
作者:Sunil K. Mandal、Matthew S. Sigman
DOI:10.1021/jo034717r
日期:2003.9.1
(-)-sparteine for a more practical achiral base in the aerobic oxidativekineticresolution of secondary alcohols is described. Carbonate bases are the most effective of those screened and allow for effective kineticresolution of benzylic, allylic, and aliphatic substrates. The procedure was also successfully extended to the oxidative desymmetrization of meso diols.
Scope of Enantioselective Palladium(II)-Catalyzed Aerobic Alcohol Oxidations with (−)-Sparteine
作者:Sunil K. Mandal、David R. Jensen、Jacob S. Pugsley、Matthew S. Sigman
DOI:10.1021/jo0269161
日期:2003.5.1
Evaluation of the substrate scope for Pd(II)/ (-)-sparteine catalyzed aerobic oxidative kinetic resolution of secondary alcohols is disclosed. An improved system is found with use of tert-butyl alcohol solvent in which benzylic and aliphatic alcohols as well as alcohols containing olefins are effectively oxidatively resolved. For substrates that successfully undergo oxidative kinetic resolution, k(rel) values
β-Hydroxy ketones can be reduced to the corresponding 1,3-diols in high yields and with excellent diastereoselectivity by carrying out the reaction with BH3·pyridine in CH2Cl2 at −78 °C in the presence of TiCl4. This protocol is general and chemoselective: excellent results are obtained when the substituents are primary, secondary, tertiary alkyl chains or aromatic moieties. The presence of reducible
β-羟基酮可以通过在-78 °C 和 TiCl4 存在下与 BH3·吡啶在 CH2Cl2 中进行反应,以高产率和优异的非对映选择性还原为相应的 1,3-二醇。该方案是通用的且具有化学选择性:当取代基为伯、仲、叔烷基链或芳族部分时,可获得优异的结果。可以很好地容忍可还原的官能团如溴、硝基和氰基的存在。
Polychlorinated materials as a source of polyanionic synthons
作者:Albert Guijarro、Miguel Yus
DOI:10.1016/0040-4020(95)01014-9
日期:1996.1
the presence of a carbonyl compound 2 (1:2 molar ratio) in THF at −40°C yields, after hydrolysis, the corresponding 1,3-diols 3 in moderate yields. The process is applied to other gem-dichlorinated materials such as 7,7-dichloro[4.1.0]heptane (4), 1,1-dichlorotetramethylcyclopropane (7) and dichloromethyl methyl ether (10), using pivalaldehyde as electrophile. Starting from 1,1,1-trichlorinated compounds
Dichloromethane as a source of the CH22-synthon: A combination of an arene-catalysed lithiation and a barbier-type reaction
作者:Albert Guijarro、Miguel Yus
DOI:10.1016/s0040-4039(00)76524-5
日期:1994.1
The reaction of dichloromethane 1 with an excess of lithium powder (1:7 molar ratio) and a catalytic amount of 4,4′-di-tert-butylbiphenyl (5 mol %) in the presence of a carbonyl compound 2 (1:2 molar ratio) in tetrahydrofuran at −40°C yields, after hydrolysis, the corresponding 1,3-diols 3 in moderate yields. The process can be also applied to more complicated gem-dichloro derivatives such as 7,7-dichlorobicyclo[4