Woollins' reagent

Abstract

(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 (Chemical Equation Presented). (B) Selenocarbonyl Synthesis. The treatment of indolizine-3-aldehydes with WR gave access to the corresponding selenoaldehydes in 40-59% yield.6 (Chemical Equation Presented). (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 (Chemical Equation Presented). (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 (Chemical Equation Presented). (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 (Chemical Equation Presented). (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 (Chemical Equation Presented). (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 (Chemical Equation Presented). (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 (Chemical Equation Presented). (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 (Chemical Equation Presented). © Georg Thieme Verlag Stuttgart.