Cobalt-catalyzed alkenylation of zinc organometallics
摘要:
Organozinc halides and diorganozincs undergo cross-coupling reactions with either E- or Z-alkenyl iodides in the presence of catalytic amounts of Co(acac)(2) or Co(acac)(3) in THF:NMP at 55 degrees C leading to polyfunctional alkenes with retention of the stereochemistry of the double bond. (C) 1998 Elsevier Science Ltd. All rights reserved.
Palladium-Catalyzed Intramolecular Hydroamination of Allenes Coupled to Aerobic Alcohol Oxidation
作者:Shuifa Qiu、Yunyang Wei、Guosheng Liu
DOI:10.1002/chem.200802381
日期:2009.3.9
Taking the air! A PdII‐catalyzed intramolecular hydroamination of allenes coupled to alcohol oxidation has been developed. This reaction is performed by using a nitrogen‐based ligand under aerobic conditions, under which the molecular oxygen is used as the terminal oxidant for the reoxidation of Pd0 species to complete the catalyticcycle.
Toward the Synthesis of Cobyric Acid. Enantioselective Syntheses of Completely Differentiated Ring D Synthons
作者:Hui Wang、Carlos Tassa、Peter A. Jacobi
DOI:10.1021/ol800985m
日期:2008.7.3
Alkyne acids 11 were prepared in an enantioselective fashion from allylic ester derivatives 18 or 20 by Ireland-Claisen rearrangement, followed by Si-assisted elimination of HBr. The title compounds are attractive ring D synthons for an ongoing synthesis of cobyricacid.
炔酸 11 是由烯丙基酯衍生物 18 或 20 通过爱尔兰-克莱森重排以对映选择性方式制备的,然后是 Si 辅助消除 HBr。标题化合物是有吸引力的环 D 合成子,用于正在进行的钴酸合成。
Elaboration of a novel effective approach to enantiopure functionalised 2,2′-dialkyl-1,1′-binaphthyls by stereoconservative cross-couplings at positions 2 and 2′
作者:Peter Kasák、Martin Putala
DOI:10.1016/j.tetlet.2004.05.016
日期:2004.6
yield and the stereochemical outcome of methylations of 1,1′-binaphthyl-2,2′-dielectrophiles (ditriflate and diiodide) clearly depend on the reactivity of the organometallics used. It was found that only the Negishi reaction of a diiodide allows direct effective synthesis of non-racemic functionalised C2-symmetric 2,2′-dialkyl-1,1′-binaphthyls.
The efficient cross-coupling reaction to afford ketones from pyridine carboxylic acid chlorides and alkylzinc reagents in the presence of Pd(phen)Cl 2 is reported. In the case of chloronicotinoyl chlorides, none ofNegishi cross-coupling products of 2-chloroazine moiety was formed. The catalyst loading could be reduced up to 0.01 mol%.