Generation of phosphoranes derived from phosphites. A new class of phosphorus ylides leading to high E selectivity with semi-stabilizing groups in Wittig olefinations

Varinder K Aggarwal; J Robin Fulton; Chris G Sheldon; Javier de Vicente

doi:10.1021/ja029573x

Generation of phosphoranes derived from phosphites. A new class of phosphorus ylides leading to high E selectivity with semi-stabilizing groups in Wittig olefinations

J Am Chem Soc. 2003 May 21;125(20):6034-5. doi: 10.1021/ja029573x.

Authors

Varinder K Aggarwal¹, J Robin Fulton, Chris G Sheldon, Javier de Vicente

Affiliation

¹ School of Chemistry, University of Bristol, Cantock's Close, UK. v.aggarwal@bristol.ac.uk

PMID: 12785815
DOI: 10.1021/ja029573x

Abstract

Tosylhydrazones derived from aryl aldehydes react with t-BuOK, ClFeTPP, (MeO)3P, and aldehydes to furnish olefins with high E selectivity. These reactions occur through a Wittig-type pathway via the corresponding diazo compounds, metal carbenes and phosphorous ylides, with the water-soluble trimethyl phosphate as the byproduct. Similar reactions can also be performed using ethyl diazoacetate; however, high E selectivity was only observed in the presence of LiBr. In this case, the reaction is believed to occur via the phosphonate anion, formed through an Arbuzov reaction. Thus this olefination reaction occurs through a Horner-Wadsworth-Emmons (HWE) reaction but the phosphonate anion is generated under completely base-free conditions.