Short-lived intermediates. 8. Excited states, regioselectivity, and stereospecificity in the photochemistry of (R,S:S,R)- and (R,R:S,S)-1,2-dimethylbutyl trifluoroacetate
Short-lived intermediates. 8. Excited states, regioselectivity, and stereospecificity in the photochemistry of (R,S:S,R)- and (R,R:S,S)-1,2-dimethylbutyl trifluoroacetate
Stereochimie de quelques reactions entre aldehydes et reactifs de Grignard satures et allyliques
作者:H. Felkin、Y. Gault、G. Roussi
DOI:10.1016/s0040-4020(01)92953-9
日期:1970.1
γ-dimethylallyl magnesium bromides) and secondary alkyl [s-butyl magnesium bromide and (1,2-dimethylpropyl) magnesium chloride] Grignardreagents to form pairs of diastereoisomeric alcohols R′—CHMeCHOH—R (R′ = CH2CH, CH2CMe, Et and iPr, respectively). The reactions involving the secondary alkylGrignardreagents are not stereoselective; those involving the allylic Grignardreagents show some stereoselectivity
A novel concept for catalytic epoxide alkylation has been developed. Lewis bases like phosphanes, arsanes, stibanes, and sulfides were found to catalyze the alkylation of symmetrical epoxides with trialkylaluminum compounds very effectively at a 5 mol % level. Cyclic as well as acyclic epoxides were readily alkylated in good yields. In reactions with terminal epoxides a significant enhancement of rate
已经开发了催化环氧化物烷基化的新概念。发现路易斯碱(如磷烷、砷烷、锑和硫化物)在 5 mol% 的水平下非常有效地催化对称环氧化物与三烷基铝化合物的烷基化。环状和无环环氧化物很容易以良好的产率烷基化。在与末端环氧化物的反应中,在路易斯碱催化过程中注意到速率和/或区域选择性的显着提高。路易斯碱与路易斯酸性铝试剂的配位由 27 Al 和 31 P NMR 光谱证明,并建议形成更亲核的烷基化剂。
Lewis base-catalyzed addition of triethylaluminum to epoxides
作者:Christoph Schneider、Jörg Brauner
DOI:10.1016/s0040-4039(00)00332-4
日期:2000.4
Lewis bases like phosphines, arsines, and antimonies catalyze the nucleophilic addition of triethylaluminum to epoxides very efficiently. They are proposed to coordinate to triethylaluminum with formation of monomeric and more reactive triethylaluminum Lewis base adducts.
The subject invention relates to novel P2X
3
receptor antagonists that play a critical role in treating disease states associated with pain, in particular peripheral pain, inflammatory pain, or tissue injury pain that can be treated using a P2X
3
receptor subunit modulator.
A new class of easily accessible and stable imidazolin-2-ylidenes has been synthesized where the side chains are comprised of substituted naphthyl units. Introduction of the naphthyl groups generates C-2-symmetric (rac) and C-s-symmetric (meso) atropisomers, and interconversion between the isomers is studied in detail both experimentally and computationally. Complete characterization of the carbenes includes rare examples of crystallographically characterized saturated NHC structures. Steric properties of the ligands and an investigation of their stability are also presented. In catalysis, the new ligands show versatility comparable to the most widely used NHCs IMes/SIMes or IPr/SIPr. Excellent catalytic results are obtained when either the NHC salts (ring-opening alkylation of epoxides), NHC-modified palladium compounds (C-C and C-N cross-couplings), or NHC-ruthenium complexes (ring-closing metathesis, RCM) are employed. In several cases, this new ligand family provides catalytic systems of higher reactivity than that observed with previously reported NHC compounds.