Room‐temperature carbon–sulfur bond formation from Ni(II) σ‐aryl complex via cleavage of the S–S bond of disulfide moieties

Abstract

The formation of ArSY (Y: C(= S)NMe 2 , Ph, P(= O)(OEt) 2 ) by reductive elimination from s-aryl complexes (M(PPh 3 ) 2 PhBr, M = Ni, Pd), associated with disulfides (YSÀSY, Y: C(=S)NMe 2 (1), Ph (2), P(=O)(OEt) 2 (3)), at ambient temperature, has been investigated. Various mechanistic features of disulfide bond (SÀS) cleavage have been elucidated using disulfide 1 by 31 P NMR spectroscopy and matrix-assisted laser desorption/ionization-time of flight mass spectrometric investigations. Based upon the results of nucleophilic cleavage of the SÀS bond by PPh 3 , studies of the reductive elimination process show that when M(PPh 3 ) 2 PhBr is mixed with disulfide 1, competitive reactions occur between the PPh 3 ligand, disulfide 1 and a trace amount of water, leading to low CÀS coupling yields; an oxidation reaction of PPh 3 with disulfide and water occur prior to CÀS cross-coupling, and phosphonium ion intermediates are likely involved. However, when the disulfide 1 is pretreated with PPh 3 , the Ni(II) s-aryl complex affords the CÀS coupling product nearly quantitatively at room temperature. The pretreatment method is also effective for the coupling reaction of disulfide 2 and Ni(II) s-aryl complex. The difference between Ni(II) and Pd (II) s-aryl complexes on CÀS bond formation by reductive elimination can be explained by the affinity of metal for the thiolate ligands derived from the cleaved disulfide.

Novel Copper(II) Thiodibenzoic Acid Coordination Polymers by in situ Extrusion of Sulfur from 2,2′‐Dithiodibenzoic Acid and the Unique Oxidation of Disulfide to Sulfate

“…It is reported in literature that heterocyclic disulfide compounds can undergo either insertion or extrusion of sulfur or oxidation of sulfur to sulfonate ion 19,26–31. Such S–S and C–S cleavage and rearrangement reaction or oxidation generally proceed under solvothermal conditions32–34 via oxidative cleavage, radical‐assisted cleavage or nucleophilic cleavage, accompanied by a change in oxidation state of the metal in some cases 35. In a previous study, Zhu et al reported the reaction of bis[4‐pyridin‐2‐yl)pyrimidinyl] disulfide (ppds) with Cu(NO 3 ) 2 under ambient temperature, in which ppds was turned into its trisulfide 2‐ppts and monosulfide 2‐pps, prior to coordination 19.…”

Arylation of Axially Chiral Phosphorothioate Salts by Dinuclear PdI Catalysis

“…However, when we subjected various Pd 0 catalysts to iodobenzene and NMe 4 [SP(=O)(OPh) 2 ], such as Pd(PPh 3 ) 4 or Pd 2 (dba) 3 /dppf, no coupling was observed (see Figure A). Moreover, when we subjected the phosphorothioate salt to a Pd II complex and heated the corresponding mixture, we did not observe the corresponding product 2 . Our computational studies support this observation, indicating that the iodide/phosphorothioate exchange at [L n Pd (II) (Ph)(I)], followed by reductive elimination of Ar−SP(=O)(OPh) 2 has a prohibitively high activation free energy barrier of Δ G ≠ ≥30 kcal mol −1 and is endergonic.…”

Simple procedure for mono- and bis-end-functionalization of regioregular poly(3-hexylthiophene)s using chalcogens

“…12 In this context, we recently reported nickel-catalysed C-S bond formation at room temperature. 13 In the paper, we used a s-aryl nickel complex for C-S bond formation in small molecules. When using the Kumada catalyst transfer polymerization (KCTP) for the controlled synthesis of P3HT, we know that the s-aryl Ni complex remains on the growing end of the p-conjugated polymer as a s-aryl nickel complex.…”