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Synlett 2010(9): 1426-1427  
DOI: 10.1055/s-0029-1219908
SPOTLIGHT
© Georg Thieme Verlag Stuttgart ˙ New York

Triphenylphosphine Dibromide

Garima*
Green Synthesis Lab, Department of Chemistry, University of ­Allahabad, Allahabad 211002, Uttar Pradesh, India
e-Mail: rinku_garima1234@yahoo.com;
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Publication History

Publication Date:
10 May 2010 (online)

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Introduction

Triphenylphosphine dibromide (TPPDB, PPh3Br2), originally synthesized by Horner and his co-workers, [¹] has shown significant synthetic versatility over the course of the last decades in organic synthesis. It has been used extensively in various organic transformations, such as bromination of alcohols, phenols, and enols, cleavage of ethers and acetals to alkyl bromides, cyclization of β- and γ-amino alcohols to aziridines and azetidines, conversion of carboxylic acid derivatives into acyl bromides, bromination or dehydration of carboxamide groups and epoxide opening to vicinal dibromides. [²] Some of these resulting compounds have been reused in total syntheses of complex natural products during the final steps. Thus, the chemoselectivity and predictable reactivity of triphenylphosphine dibromide makes it a noteworthy and useful reagent. It also finds application in the synthesis of ¹8F-4-fluorobenzyltriphenylphosphonium bromide, a new class of positron-emitting lipophilic cations, acting as myocardial per fusion PET tracers. [³]

Triphenylphosphine dibromide is a colorless crystalline hygroscopic solid (mp 235 ˚C) that is readily prepared before use by addition of an equimolar amount of bromine to triphenylphosphine in anhydrous diethyl ether at 0 ˚C (Scheme  [¹] ). [4] It is a molecular compound in the solid state, but ionises in dichloromethane to form [Ph3PBr]+Br-. [5]

Scheme 1