Herein we present the first catalytic enantioselective Wittigreaction. Chiral mono- and diphosphines were employed as catalysts for the desymmetrization of a prochiral ketone. The reaction was performed under microwave dielectric heating as well as under conventional heating. Selected catalysts led to moderate to good yields and enantioselectivities. In the presence of (+)-1,2-bis[(2S,5S)-2,5-dim
Phosphetane Oxides as Redox Cycling Catalysts in the Catalytic Wittig Reaction at Room Temperature
作者:Lars Longwitz、Anke Spannenberg、Thomas Werner
DOI:10.1021/acscatal.9b02456
日期:2019.10.4
renewable solvent. The intermediates of the Wittig reaction were analyzed by 31P NMR spectroscopy, and in situ NMR experiments confirmed phosphaneoxide as the resting state of the catalyst. Further kinetic investigations revealed a striking influence of the base on the rate of phosphaneoxidereduction.
We identified 2-phenylisophosphindoline 2-oxide as a suitable and potentially tunable catalyst for the catalytic Wittigreaction of aldehydes with activated organohalides. This catalyst was obtained by a straightforward two-step synthesis. Trimethoxysilane proved to be an efficient reducing agent for the in situ generation and regeneration of the catalyst from the corresponding phosphane oxide. Sodium
Utilization of Me<sub>3</sub>SiSnBu<sub>3</sub>-F<sup>−</sup>in Organic Synthesis. Reaction of an Allyl Anion Generated from Me<sub>3</sub>SiSnBu<sub>3</sub>and CsF
作者:Atsushi Kinoshita、Miwako Mori
DOI:10.1246/cl.1994.1475
日期:1994.8
The intramolecular cyclization of an allyl halide having a carbonyl group proceeded smoothly via an allyl anion in the presence of Me3SiSnBu3 and CsF in DMF. The resultant products were converted into useful compounds for the synthesis of natural products.
Enantiomerically Pure Octahydronaphthalenone and Octahydroindenone: Elaboration of the Substrate Overcame the Specificity of Yeast-Mediated Reduction
作者:Ken-ichi Fuhshuku、Mina Tomita、Takeshi Sugai
DOI:10.1002/adsc.200303004
日期:2003.6
change into an octahydroindene skeleton retarded the enzymatic reduction and the enantioselectivity fell to E=5–16. Further structural variation into a bicyclo[3.3.0] skeleton led to an exclusive 1,4-conjugate reduction of the α,β-unsaturated carbonyl group, and the above results suggested the participation of plural oxidoreductive enzymes in the whole cell. In turn, among the 2,2-disubstituted cycloalkanediones