This so-called Wittig reaction has a number of advantages over other olefination methods; in particular, it occurs with total positional selectivity (that is, an alkene always directly replaces a carbonyl group). By comparison, a number of other carbonyl olefination reactions often occur with double-bond rearrangement. In addition, the factors that influence Eand Z-stereoselectivity are well un...

The Wittig reaction of butylidenetriphenylphosphorane with benzaldehyde using LiHMDS as base in THF was studied. The stereochemical drift (different ratio obtained in alkenes versus oxaphosphetane intermediates) was followed by low-temperature 1D NMR techniques. A retro-Wittig reaction is demonstrated using 13C and 31P saturation transfer experiments and homonuclear DPFGSE-ROE techniques.

A key intermediate, difluoromethylene phosphobetaine, in the Wittig reaction of ClCF2CO2Na-Ph3P with aldehydes was synthesized and characterized, which confirmed the reaction mechanism. The decarboxylation of this stable intermediate was a convenient approach for Wittig difluroolefination. Its reactivity could be adjusted by the modification of the substituent on the phosphorus.

We report the phospha-bora-Wittig reaction for direct preparation of phosphaalkenes from aldehydes, ketones, esters, or amides. The transient phosphaborene Mes*P?B–NR2 reacts with carbonyl compounds to form 1,2,3-phosphaboraoxetanes, analogues oxaphosphetane intermediates in classical Wittig reaction. 1,2,3-Phosphaboraoxetanes undergo thermal Lewis acid-promoted cycloreversion, yielding phospha...

The mechanism of the Wittig reaction has long been a contentious issue in organic chemistry. Even now, more than 50 years after its announcement, its presentation in many modern undergraduate textbooks is either overly simplified or entirely inaccurate. In this review, we gather together the huge body of evidence that has been amassed to show that the Li salt-free Wittig reactions of non-stabil...

This review surveys the literature regarding the development of catalytic versions of the Wittig and aza-Wittig reactions. The first section summarizes how arsenic and tellurium-based catalytic Wittig-type reaction systems were developed first due to the relatively easy reduction of the oxides involved. This is followed by a presentation of the current state of the art regarding phosphine-catal...

protonation of the reactive intermediates generated in the raction between dalkyl acetylenedicarboxylates and triphenylphosphine by isonitrosoacetophenone leads to vinyltriphenylphosphonium salts, which undergo intramolecular wittig reaction to produce dalkyl 4-phenyl-n-hydroxypyrrole-2,3-dicarboxylates in moderate yields.

Mechanochemistry is maturing as a discipline and continuing to grow, so it is important to continue understanding the rules governing the system. In a mechanochemical reaction, the reactants are added into a vessel along with one or more grinding balls and the vessel is shaken at high speeds to facilitate a chemical reaction. The dielectric constant of the solvent used in liquid-assisted grindi...