Triphenylphosphine Dibromide

Abstract

(A) Preparation of Alkyl, Allyl, and Aryl Bromides: Horner and co-workers1 demonstrated the application of triphenylphosphine dibromide for the conversion of alcohols and phenols into bromides. It has advantages over the other phosphorus-based reagents in effecting substitution without elimination or molecular rearrangement with inversion of the product configuration. It becomes the reagent of choice for the conversion of various types of alcoholcontaining sensitive functionalities, such as cis double bonds and ketals, into the corresponding bromides6.figure presented. (B) Ring Opening of Aziridines: Kumar and co-workers7 have reported the use of PPh3Br2 as highly efficient reagent for the ring opening of aziridines affording β-bromo amines. The method works effectively for both activated and non-activated aziridines in excellent yields within a short period of time. Figure presented. (C) Synthesis of Vinyl Bromides: Kamei and co-workers8 have developed a new synthetic method for the preparation of vinyl bromides from acyclic and cyclic ketones. Figure presented. (D) Conversion of TBDMS and THP Ethers into Bromides: PPh3Br2 is a mild and highly effective reagent for the direct cleavage of TBDMS and THP ethers into bromides9. Figure presented. (E) Preparation of Esters: Salom and Kohn10 have reported a one-pot, expedient protocol for the conversion of carboxylic acids into their esters using excess triphenylphosphine dibromide, base, and alcohol. The reaction gave the esterified product in moderate to high yields. Figure presented. (F) Preparation of N-Nitrosamines and Azides: The PPh3Br2 in combination with n-u 4NNO2 has been applied successfully for the preparation of N-nitrosamines and azides from the corresponding amines and hydrazine derivatives in excellent yields11. Figure presented (G) Oxidation of Alcohols: The use of PPh3Br2 in combination with DMSO is found to be a good alternative to the classical Swern oxidation. A variety of alcohols has been oxidized under mild conditions by the DMSO PPh 3Br2 complexes12. Figure presented. (H) Nitration of Aromatic Amines: The use of PPh3Br2/AgNO 3 provides a new reagent system for the novel and highly chemoselective nitration of aromatic amines under mild reaction conditions 13.(I) Deoxygenation of Sulfoxides: The combination of Ph 3P/Br2/CuBr was found to be an effective promoter for the deoxygenation of sulfoxides and afforded the corresponding sulfides in excellent yields14. © 2010 Georg Thieme Verlag Stuttgart.