Palladium-Catalyzed Oxidative Sulfenylation of Indoles and Related Electron-Rich Heteroarenes with Aryl Boronic Acids and Elemental Sulfur

Abstract

An efficient and convenient palladium-catalyzed C-H bond oxidative sulfenylation of indoles and related electron-rich heteroarenes with aryl boronic acids and elemental sulfur has been described. This procedure provides a useful and direct approach for the assembly of a wide range of structurally diverse 3-sulfenylheteroarenes with moderate to excellent yields from simple and readily available starting materials. Moreover, this synthetic protocol is suitable for N-protected and unprotected indoles. Notably, the construction of two C-S bonds in one step was also achieved in this transformation.

Metal‐Free Thiolation of Imidazopyridines with Functionalized Haloalkanes Using Elemental Sulfur

“…Based on our results and previous reports concerning the thiolation using elemental sulfur,–, a possible reaction mechanism has been proposed (Scheme ). At high temperature, imidazopyridine 1a exists as the resonance structure A , which undergoes a nucleophilic reaction with elemental sulfur to give intermediate B [Eq.…”

“…Recently, copper‐ and cobalt‐catalyzed thiolation of imidazopyridines with aryl iodides or arylboronic acids using elemental sulfur have been reported [Scheme , Eq. (1)] –. An alkylthiolation of imidazopyridines using primary alcohols and elemental sulfur, in the presence of iodine and PPh 3 , has also been developed [Scheme , Eq.…”

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

“…The majority of methods for C–S bond synthesis use transition metal-catalyzed cross coupling of thiols and their derivatives with organohalides [ 4 – 6 ], arylboronic acids [ 7 ], aryl triflates [ 8 ], and diazonium salts [ 9 ]. Typical metals used are palladium [ 10 – 13 ], copper [ 14 – 21 ], nickel [ 22 – 24 ], iron [ 25 – 29 ], cobalt [ 30 – 32 ], and rhodium [ 33 – 34 ]. Aryl sulfides are also synthesized by cross coupling of thiols and aryl Grignard/arylzinc reagents [ 35 – 36 ].…”

Photocatalytic direct C–S bond formation: facile access to 3-sulfenylindoles via metal-free C-3 sulfenylation of indoles with thiophenols

“…3 Because of the importance of such compounds, numerous synthetic approaches of 3-sulfenylindoles have been successfully established in previous literature. 4,5 Importantly, direct functionalization of indoles at the C-3 position is a valuable approach for the effective preparation of 3-sulfenylindoles. So far, a variety of sulfenylating agents such as arylsulfenyl halides, 6 arylsulfonyl chlorides, 7 sulfonyl hydrazides, 8 diaryl disuldes, 9 N-thiophthalimides, 10 O,Sacetals, 11 arylsulfoniumsalts, 12 sulnic acids, 13 Bunte salts, 14 and thiols 15 have also been employed for C3-sulfenylation of indoles.…”