Complex Allylation by the Direct Cross-Coupling of Imines with Unactivated Allylic Alcohols
作者:Masayuki Takahashi、Martin McLaughlin、Glenn C. Micalizio
DOI:10.1002/anie.200900236
日期:2009.5.4
stereoselective: The convergent coupling of allylic alcohols with imines to deliver stereodefined homoallylic amines is described (see scheme). The process proceeds with net allylic transposition without the intermediacy of allylic organometallic reagents. Two stereodefined centers and a geometrically defined di‐ or trisubstitutedalkene are forged with high selectivity.
Conversion of Allylic Alcohols to Stereodefined Trisubstituted Alkenes: A Complementary Process to the Claisen Rearrangement
作者:Justin K. Belardi、Glenn C. Micalizio
DOI:10.1021/ja8074242
日期:2008.12.17
A stereoselective method for the conversion of allylic alcohols to (Z)-trisubstituted alkenes is presented. Overall, the reaction sequence described is stereochemically complementary to related Claisen rearrangement reactions--processes that typically deliver the stereoisomeric trisubstitutedalkene containing products.
Cyclopentyl and cyclopropylmethanol derivatives were efficiently prepared through a chemoselective hydrozirconation reaction of (1-butenyl)oxirane and vinyloxirane with Cp2ZrHCl. However, the attemped reaction of (1-pentenyl)oxirane or (1-propenyl)oxirane failed to yield cyclohexyl or cyclobutylmethanols. The ring formation was stereospecific and proceeded with the inversion of the configuration at the reacting oxirane carbon. The origin of stereospecificity and the stereoselectivity in the formation of cyclopropylmethanols was presumed by the approach of the Schwartz reagent from the less hindered site of the stable gauche-conformer of the vinyloxirane compound in the transition state. (Cyclopropylmethyl)amine derivatives were also prepared by the treatment of vinylaziridine derivatives with Cp2ZrHCl. (C) 1997 Elsevier Science Ltd. All rights reserved.
General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand
Remarkably simple IrIII catalysts enable the isomerization of primary and sec‐allylicalcohols under very mild reaction conditions. X‐ray absorption spectroscopy (XAS) and mass spectrometry (MS) studies indicate that the catalysts, with the general formula [Cp*IrIII], require a halide ligand for catalytic activity, but no additives or additional ligands are needed.
非常简单的Ir III催化剂可在非常温和的反应条件下实现伯醇和仲烯丙基醇的异构化。X射线吸收光谱(XAS)和质谱(MS)研究表明,通式为[Cp * Ir III ]的催化剂需要卤化物配体才能发挥催化活性,但不需要添加剂或其他配体。