Related Experiment Video
Updated: May 2, 2026

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
A Fresh Twist on the Phospha-(Aza)-Wittig Reaction
Chenyang Hu1,2, Maren Pink1, Jose M Goicoechea1
1Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States.
Abstract:
The reactivity of an unsupported phosphinidene oxide, BnArNP═O (Bn = benzyl; Ar = bulky aryl group), as the electrophilic partner in Wittig reactions with ylides is described. Reactions with methylene-triphenylphosphorane (H2C═PPh3) and ethylidene-triphenyl-phosphorane (HMeC═PPh3), proceed as expected, giving rise to the phosphaalkene metathesis products and triphenylphosphine oxide. This reaction can be extended to other ylides such as N-(triphenylphosphoranylidene)methanamine (MeN═PPh3), to afford an aminoiminophosphane BnArNP═NMe. In these reactions the phosphinidene oxide plays the role of an electrophile, which would typically be the remit of an organic carbonyl in classical Wittig reactions. Further mechanistic insight into such transformations can be gained by altering the nature of the phosphorus-ylide. Upon reacting BnArNP═O with H2C═PMe3 (which possesses a smaller, more Lewis basic, phosphine) an alternative product is formed. This transformation supports the formation of a betaine intermediate that subsequently undergoes hydrogen-migration to afford an oxidized phosphorus(V) compound related to phosphorus acid.
More Related Videos
10:10Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes
Published on: July 28, 2018
07:36Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
Related Concept Videos
Aldehydes and Ketones to Alkenes: Wittig Reaction Overview
α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction
Reactions at the Benzylic Position: Oxidation and Reduction
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
Aldehydes and Ketones to Alkenes: Wittig Reaction Mechanism
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom...
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism