A Facile and Mild Method for the Synthesis of Terminal Bromofluoroolefins via Diethylzinc-Promoted Wittig Reaction

Abstract

[reaction: see text] Synthesis of 1-bromo-1-fluoroolefins was achieved in good yields via a Wittig reaction promoted by diethylzinc, even with nonactivated aldehydes and ketones as starting materials.

First enantioselective reductive amination of α-fluoroenones

“…We chose the reduction of 5a as reaction model (Scheme 4). It has to be noted that the reaction could afford hydroxylamine ether 10a along with expected amine 1a.…”

“…We already described efficient access to bromofluoroolefins 3 via a Wittig-type reaction [4] and, more recently, to compounds 2 via a Negishi coupling reaction [5]. At this stage, we were therefore interested in short sequences allowing the transformation from unsaturated ketones 2 to chiral allylic primary amines 1.…”

Site-specific preparation of 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes via base-catalyzed cyclization of enyne derivatives

“…(2) Pannecoucke and coworkers employed a similar process to selectively remove the (E)-1-bromo-1-fluoroalkene via selective reaction of the (E)-alkene with BuLi/ZnCl 2 and Pd(0) catalyst [34]. Recovery of the (Z)-alkene provided the (Z)-1-bromo-1-fluoroalkene in 89% yield (Eq.…”

Phosphines and Related Tervalent Phosphorus Systems

“…495,496 Addition of diethylzinc to the triphenylphosphine-tribromofluoromethane system leads to improvements in the generation of the ylide Ph 3 P¼CBrF, and its subsequent Wittig reactions with carbonyl compounds in the synthesis of bromofluoroalkenes. 497 The triphenylphosphine-trichloroacetonitrile system has been used as a reagent for the N-acylation of polymer-supported benzylamines 498 and in a general procedure for the preparation of esters from carboxylic acids. 499 The reaction of triphenylphosphine with bis(trichloromethyl) carbonate provides a reagent system that converts thiols into the related disulfides.…”