Kinetic study on debromination of vic-dibromides with trivalent phosphorus compounds

✍ Scribed by Shinro Yasui; Kenji Itoh; Atsuyoshi Ohno

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 135 KB
• Volume: 12
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.1035

✦ Synopsis

Abstract

Various types of trivalent phosphorus compounds (1) brought about reductive debromination of vic‐dibromides (2) to afford olefins. The reaction was accelerated by either electron‐releasing substituents on the phosphorus of 1 or electron‐withdrawing substituents on the α‐carbon of 2. The substituent effects, along with the stereochemistry of the reaction, are consistent with an E1CB‐like mechanism for the elimination of the two bromine atoms. That is, 1 initially undergoes nucleophilic attack upon a bromine of 2. At the transition state, a fractional positive charge is developed on the phosphorus of 1 and a fractional negative charge on the carbon of 2. This mechanism suggests the importance of an electronic character of the vic‐dibromide in determining the relative ease of bromophilicity, carbophilicity, and basicity of the phosphorus of a trivalent phosphorus compound in a reaction with the dibromide. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:217–222, 2001