The Action of Raney Nickel upon Sulfur Compounds. VI.¹ Formation of Biphenyl Derivatives

Chemoselective Carbon‐Carbon Cross‐Coupling via Palladium‐Catalyzed Copper‐Mediated CS Cleavage of Disulfides

“…They are useful sulfenylating reagents and were widely used as sulfenyl and sulfinyl reagents through SS cleavage with various reagents 18–23. However, there is a notable absence of examples of couplings of disulfides for the formation of CC bonds between arylboronic acids and disulfides (Scheme ) 24,25…”

“…At the same time, O. Kwon et al reported the Pd(0)-catalyzed and copper(I)-thiophene-2-carboxylate-(CuTC)-mediated desulfitative couplings of nitrothioethers with boronic acids. [24,25] Based on the wide ranging biological activity of 3,4dihydropyrimidinones [26] and their utilization as important precursors in the synthesis of pyrimidine bases, [27] combined with our previous experience on the synthesis of 3,4-dihydropyrimidinone derivatives, [28] we selected the coupling of 1,2-di(pyrimidin-2-yl) disulfide 1a (for the preparation, see the Supporting Information) and phenylboronic acid (2a) as the model reaction. They are useful sulfenylating reagents and were widely used as sulfenyl and sulfinyl reagents through S À S cleavage with various reagents.…”

Efficient Synthesis of Diaryl Sulfides by Copper-catalysed Coupling of Aryl Halides and Thioacetate in Water

“…1 H NMR (400 MHz, CDCl 3 /TMS): δ = 7.43-7.27 (m, 10H); 13 Di(4-methylphenyl) sulfide 26 (2b), Table 2, entries 2 and 9: Colourless oil. 1 Di(3-methylphenyl) sulfide 38 (2c), Table 2, entries 3 and 10: Colourless oil. 1 H NMR (400 MHz, CDCl 3 /TMS): δ = 7.35-6.92 (m, 8H), 3.93 (s, 6H).…”

The Action of Raney Nickel on Organic Sulfur Compounds.

“…The behavior of sulfur compounds in the presence of Raney nickel degassed by heating in vacuo at 100°( Raney Ni 100) and 200°( Raney Ni 200) has been studied by Hauptmann, Wladislaw, and Camargo (248,249,251). Later the degassing temperature was raised to 500°( Raney Ni 500) (247,252) nickel powder obtained by reducing nickel oxide with hydrogen at 320°( 247) or by decomposing nickel oxalate at 350°( 246) has been employed; the former was degassed at 200°in vacuo before being used, the latter was used without pretreatment. W-7 Raney nickel heated in vacuo (12 mm.)…”

“…3. "Dimerization" (29,33,36,248,249,252) and cyclization (64,350,351), as well as terphenyl formation (247), which are best understood on the basis of a homolytic mechanism. Terphenyl formation from benzene derivatives has always been considered characteristic for the occurrence of phenyl radicals (18,143).…”