Nucleophilic diaddition of secondary phosphine sulfides to acetylene and methylacetylene

Abstract

Secondary phosphine sulfides react with acetylene and methylacetylene in the system КOH-DMSO (50 °C, 2-3 h) to form the corresponding tertiary bis phosphine sulfides in high yield (up to 97%). Specific features of the NMR spectra ( 1 H, 13 C, and 31 P) of compounds obtained are discussed.Bis phosphine sulfides are under intensive study as efficient polydentate ligands for the design of metal com plex catalysts, 1-4 antipyrenes, 5 intermediate products for the development of fluorescent and electroluminescent sensors, 6 as well as promising solvents and intermediates for the preparation of semiconducting nanomaterials. 7 Bis phosphine sulfides with chiral centers are of particular value. 8 Reduction of the latter leads to the corresponding optically active bis phosphines, 9 which are widely used in the catalytic stereoselective synthesis. 10,11 At the same time, methods for the preparation of bis phosphine sul fides, as a rule, are multistep and laborious and are based on toxic phosphorus halides and organometallic reagents. 12 One of the most convenient approaches to the synthesis of tertiary bis phosphine chalcogenides is the reaction of nucleophilic addition of two molecules of secondary phos phine chalcogenide to acetylenes. This reaction is at the time under intensive study on the example of "activated" acetylenes with the triple bond bearing electron with drawing groups. 13-16 The reaction of acetylene and its first and the most available homolog (methylacetylene) with secondary phosphine sulfides has not been imple mented so far. Moreover, it was reported 13 that diphenyl phosphine sulfide does not react with electron saturated acetylenes (hexyne, phenylacetylene) under nucleophilic conditions, for example, in the system КОH-H 2 OMeCN.In the present work, in order to develop a straight forward method for the synthesis of new bis phosphine sulfides, the reaction of nucleophilic addition of second ary phosphine sulfides 1a,b, easily available from styrenes, * Dedicated to Academician A. I. Konovalov in honor of his 75th anniversary. red phosphorus, and elementary sulfur, to acetylene and methylacetylene has been studied. 17,18 Experiments showed that virtually no reaction takes place in the system КОH-THF. At the same time, when superbasic catalytic system КОH-DMSO 19 was used, the nucleophilic addition of two molecules of secondary phos phine sulfide proceeds efficiently at mild temperatures (50 °C, 2-3 h) under pressure of acetylene (autoclave, the initial pressure of 14 atm) or in the channel system (in the case of methylacetylene) with the formation of bis adducts 2a-c in high yield (Scheme 1). Scheme 1R 1 = R 2 = H (a); R 1 = Bu t , R 2 = H (b); R 1 = H, R 2 = Me (c)

Catalyst- and Solvent-Free Stereoselective Addition of Secondary Phosphine Chalcogenides to Alkynes

“…The obtained adducts 13a-k were fully characterized by NMR ( 1 H, 13 C, 31 P, and, when appropriate, 28 Si, 77 Se) and IR spectroscopy, and their composition was verified by microanalysis. In general, 1 H, 13 C and 31 P NMR spectra of compounds 13a-k reveal characteristic peaks of the corresponding atoms in their typical regions.…”

“…1 H NMR chemical shifts are expressed with respect to residual protonated CDCl 3 (δ = 7.27 ppm), which served as an internal standard. 13 C NMR shifts are expressed with respect to CDCl 3 (δ = 77.0 ppm). TMS, 85% H 3 PO 4 /D 2 O and Me 2 Se were used as external standards for 28 Si, 31 P, and 77 Se NMR, respectively.…”