Woollins’ Reagent

María Ángeles López-García

doi:10.1055/s-0029-1217802

Synlett 2009(14): 2373-2374
DOI: 10.1055/s-0029-1217802

SPOTLIGHT

Woollins’ Reagent

María Ángeles López-García
Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla. c/ Profesor García González 1, Apartado 1203, 41012-Seville, Spain
e-Mail: marlopgar@alum.us.es;

Abstract

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Biographical Sketches

María Ángeles López-García was born in Marchena, Seville, in 1983. She received her degree in Chemistry at the University of Seville, in 2006. She is currently carrying out her Ph.D. studies at the same University under the supervision of Professor José G. Fernández-Bolaños. Her research interests focus on the synthesis of antioxidant polyphenols and related structures.

Introduction

Woollins’ Reagent {WR, 2,4-diphenyl-1,3-diselenadi-phosphetane-2,4-diselenide, [PhP(Se)(µ-Se)]₂} is a selenium analogue of the well-known Lawesson’s reagent, [4-MeOC₆H₄P(S)(µ-S)]₂. Compared to other selenium reagents, the deep-red crystals of WR have less unpleasant chemical properties, are easy to prepare, and safely handled in air. [¹] WR is used in the synthesis of selenium-containing organic compounds and P-Se heterocycles. [²]

Woollins and co-workers initially prepared WR from the pentamer (PhP)₅, [³] which is an air-sensitive compound with a lingering stench. For this reason, they have developed a new method preparing WR producing material of high purity in high yield. [4] This compound is now commercially available.

Figure 1

Abstracts


(A) Stereoselective Synthesis of Olefins by a Reductive Coupling Reaction. Aromatic ketones and aldehydes were converted into symmetrical and asymmetrical E-olefins by reaction with WR in 53-100% yield. A mechanism involving a Wittig-like reaction intermediate has been proposed. [5]
(B) Selenocarbonyl Synthesis. The treatment of indolizine-3-aldehydes with WR gave access to the corresponding selenoaldehydes in 40-59% yield. [6]
(C) Synthesis of N,N-Disubstituted Selenoamides by O-Se Exchange. The selenation of N,N-disubstituted amides using WR provided a general and straightforward route to the corresponding selenoamides. This reaction was carried out under mild conditions and afforded the selenoamides in higher yields (21-85%) than using other selenation reagents. The yield decreased with the bulkiness of the nitrogen substituents. [7]
(D) Synthesis of Primary Arylselenoamides. Woollins and co-workers have developed a new method for the synthesis of primary arylselenoamides, which were obtained by the reaction of arylnitriles with WR and subsequent addition of water in moderate to excellent yields (60-100%). [8]
(E) Synthesis of Sulfides by Deoxygenation of Sulfoxides. Woollins’ reagent allowed the deoxygenation of a series of sulfoxides to sulfides in good to excellent yields (81-99%). The reaction proceeded by refluxing a toluene suspension of the cited reagent and the corresponding sulfoxides. The reaction has been found to be a very useful approach in organic synthesis because of the simple work-up, mild conditions, high selectivity and high conversion of substrates. [¹]
(F) Synthesis of 1,3-Diarylbenzo[c]selenophenes. The reaction of benzo[c]furans with WR has been used in the synthesis of a series of 1,3-diarylbenzo[c]selenophenes in 55-70% yield involving a selenium transfer reaction. [9] [¹0]
(G) Synthesis of 2,5-Disubstituted 1,3,4-Selenadiazoles and Selenophenes. Recently, Woollins and co-workers have described an efficient method for the synthesis of 2,5-disubstituted 1,3,4-selenadiazoles by the reaction of WR and 1,2-diacylhydrazines. [¹¹] Similarly, 2,5-disubstituted selenophenes were obtained from 1,4-diketones. [²]
(H) Synthesis of Vinylic P-Se Heterocycles and Bis-Heterocycles. Five-membered P(Se)Se₂C₂ heterocycles have been synthesized by insertion of a Ph(Se)PSe₂ fragment from WR into the alkyne triple bonds. [¹²] On the contrary, the reaction of WR with 1,4-di-tert-butyl-1,3-diyne gave an unusual four-membered P(Se)SeC₂ ring and a fused bis-heterocyclic compound with two five-membered rings. [¹³]
(I) Synthesis of Selenazadiphospholaminediselenides. Woollins and co-workers have synthesized selenazadiphospholaminediselenides by the reaction of phenylalkylcyanamides with WR in moderate yields (42-43%). The novel heterocycles were hydrolyzed to the unusual zwitterionic cabamidoyl(phenyl)phosphinodiselenoic acid in high yields (96-98%). [¹4]