A Rh(III)-catalyzed one-pot reaction of N-phenoxyacetamides, ketones, and hydrazines for a facile access to disubstituted and trisubstituted ethylenes is reported. In this method, various ketones are transformed into donor–donor diazo compounds, which engage in insertion with N-phenoxyacetamides, following β-H elimination under Rh(III) catalysis to generate (E)-polyaryl-substituted olefins. This chemistry
Grubbs' Catalyst in Paraffin: An Air-Stable Preparation for Alkene Metathesis
作者:Douglass F. Taber、Kevin J. Frankowski
DOI:10.1021/jo030005p
日期:2003.7.1
A homogeneous mixture of Grubbs' catalyst in paraffin wax was shown to catalyze three important types of metathesis reactions: ring-closing metathesis, alkene dimerization, and alkene cross-metathesis (e.g., 11 --> 13). This catalyst preparation demonstrated no loss in catalytic activity after 22 months of storage open to the air.
Asymmetric Reduction of Imines with Trichlorosilane, Catalyzed by Sigamide, an Amino Acid-Derived Formamide: Scope and Limitations<sup>†</sup>
作者:Andrei V. Malkov、Kvetoslava Vranková、Sigitas Stončius、Pavel Kočovský
DOI:10.1021/jo900561h
日期:2009.8.21
nonaromatic ketones 1−5, in which the steric difference between the alkyl groups R1 and R2 is sufficient. Simple nitrogen heteroaromatics (8a,b,d) exhibit low enantioselectivities due to the competing coordination of the reagent but increased steric hindrance in the vicinity of the nitrogen (8c,e) results in a considerable improvement. Cyclic imines 32d-d exhibited low to modest enantioselectivities.
Highly Efficient Chromium-Catalyzed Oxidation of Secondary Benzylic Alcohols by Aqueous 70%<i>tert</i>-Butyl Hydroperoxide
作者:Jacques Muzart、Abdelaziz N'ait Ajjou
DOI:10.1055/s-1993-25941
日期:——
The oxidation of secondary benzylic alchols to ketones by the chromium(VI) oxide/tert-butyl hydroperoxide system is compatible wih the presence of methyl, halide, methoxy, acetoxy or nitro substituents on the aryl group and of an unsaturation on the alkyl side chain. Benzyl alchol led to a mixture of benzaldehyde and benzoic acid.
Cyclopentane Formation from Flexible Precursors Using Samarium(II) Reagents
作者:Christopher D. Aretz、Humberto Escobedo、Bryan J. Cowen
DOI:10.1002/ejoc.201800102
日期:2018.4.30
This study presents three efficient methods for five‐membered ring carbocycle synthesis using samarium(II) reagents. Simple organic starting materials engage in intramolecular Reformatsky aldol, enolate alkylation, and pinacol cyclizations. A promising lead result has also been established demonstrating enantioselectivity in a chiral ligand controlled Reformatsky aldol reaction.