Synthesis of biaryls via intramolecular free radical ipso-substitution reactions

Radical Smiles Rearrangement: An Update

“…Heteroarylsulfonates or sulfonamides submitted to optimized reaction conditions afforded mainly or exclusively 1,5-ipso-substitution products. Extension of this reaction to benzylic sulfonamides or sulfonates evidenced a preference for the 1,7-cyclization path even if in some cases 1,6-ipso-products were isolated in small quantity [31]. …”

“…Heteroarylsulfonates or sulfonamides submitted to optimized reaction conditions afforded mainly or exclusively 1,5-ipso-substitution products. Extension of this reaction to benzylic sulfonamides or sulfonates evidenced a preference for the 1,7-cyclization path even if in some cases 1,6-ipso-products were isolated in small quantity [31]. As part of a study to explore new transition-metal complexes as potential photocatalysts Barriault et al have described a light-induced reductive radical reaction of unactivated alkyl and aryl bromides using a dimeric phosphine-gold complex.…”

Synthesis of Dibenzosultams by “Transition-Metal-Free” Photoinduced Intramolecular Arylation of N-Aryl-2-halobenzenesulfonamides

“…(100), 166 (56), (29), 139 (39), 115 (9), 113 (10), (8), 84 (10), 70 (11), 69 (10), (14). e] [1,2]thiazine 5,5-dioxide (6b).…”

“…9, 133.6, 132.6, 132.4, 132.2, 128.6, 128.1, 127.6, 127.0, 126.7, 126.5, 125.1, 123.0, 122.3, 121.4, 119.7 [2,1-c] [1,2]thiazine 5,5-dioxide (6m). After evaporation of the solvent the organic phase was purified by column chromatography on silica gel eluting with pentane/ EtOAc 14, 190 (19), 189 (39), 187 (11), 109 (22), 96 (11), 95 (25), 94 (43), 82 (13).…”

“…6 For dibenzosultams the synthetic approaches are less known and are represented in Scheme 1. These protocols include intramolecular radical cyclization 7 or palladium-catalyzed intramolecular arylation 8 of 2-bromo-N-alkyl-Narylbenzenesulfonamides (A), intramolecular oxidative amination of 2-arylbenzenesulfonamides under "Transition-Metal Free" condition (B), 9 double C(sp 2 )-H palladium-catalyzed intramolecular oxidative coupling of N-arylbenzenesulfonamides (C) 10 or 1,6 radical addition of N- (2-iodophenyl) -N-methyl-benzenesulfonamide (D) 11 Radical nucleophilic substitution involving electron-transfer (ET) steps (S RN 1) 12 is a cyclic process with radicals and radical anions as intermediates. In the S RN 1 reactions carbanions and anions derived from heteroatoms can be used as nucleophiles to form new C-C or C-heteroatom bonds.…”