A Metal-Free Sulfenylation and Bromosulfenylation of Indoles: Controllable Synthesis of 3-Arylthioindoles and 2-Bromo-3-arylthioindoles

Regioselective C-H Sulfanylation of Aryl Sulfoxides by Means of Pummerer-Type Activation

A regioselective C-H sulfanylation of aryl sulfoxides with alkyl aryl sulfides in the presence of acid anhydride was developed, which resulted in the formation of 1,4-disulfanylarenes after dealkylation of initially formed sulfonium salts. The reaction began with Pummerer-type activation of aryl sulfoxides followed by nucleophilic attack of alkyl aryl sulfides. The nucleophilic attack occurred exclusively at the para positions, or at specific positions in case the para position was not available, under perfect control by the dominating sulfoxide directors regardless of any other substituents. The initially formed aryl sulfonium salts were isolable and usefully served as aryl halide surrogates for palladium-catalyzed arylation with sodium tetraarylborates.

Iodine-catalyzed cascade annulation of alkynes with sodium arylsulfinates: assembly of 3-sulfenylcoumarin and 3-sulfenylquinolinone derivatives

An efficient and environmentally benign iodine-catalyzed cascade cyclization has been achieved to afford functionalized 3-sulfenylcoumarin and 3-sulfenylquinolinone derivatives.

Synthesis of N-alkyl-3-sulfonylindoles and N-alkyl-3-sulfanylindoles by cascade annulation of 2-alkynyl-N,N-dialkylanilines

Divergent synthesis of N-alkyl-3-sulfonylindoles and N-alkyl-3-sulfanylindoles from 2-alkynyl-N,N-dialkylanilines and sulfonyl hydrazides has been described.

Palladium-catalyzed tandem addition/cyclization in aqueous medium: synthesis of 2-arylindoles

Pd-catalyzed tandem reaction of potassium aryltrifluoroborates with nitriles for the synthesis of 2-arylindoles in aqueous medium.

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

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.

Tandem approach for the synthesis of 3-sulfenylimidazo[1,5-a]pyridines from dithioesters

Iodine-mediated synthesis of 3-sulfenylimidazo[1,5-a]pyridines via C–H functionalization has been achieved using dithioesters, 2-methylaminopyridines and sulfonyl hydrazides.

Organocatalyzed CO2 Trapping Using Alkynyl Indoles

The first organocatalyzed trapping of CO2 through C-C and C-O bond formation is reported. Alkynyl indoles together with catalytic amounts of an organic base and five equivalents of CO2 resulted in the formation new heterocyclic structures. These tricyclic indole-containing products were successfully prepared under mild reaction conditions from aromatic, heteroaromatic, and aliphatic alkynyl indoles with complete regioselectivity. Further investigations suggest that C-C bond formation is the initial intermolecular step, followed by lactone-forming C-O bond formation.

Metal- and base-free syntheses of aryl/alkylthioindoles by the iodine-induced reductive coupling of aryl/alkyl sulfonyl chlorides with indoles

Iodine-induced reductive coupling of aryl/alkyl sulfonyl chlorides with indoles leading to various substituted aryl/alkylthioindoles has been accomplished.

Iodine–triphenylphosphine mediated sulfenylation of imidazoheterocycles with sodium sulfinates

An efficient approach to sulfenyl imidazoheterocycles has been developed via iodine–triphenylphosphine mediated direct sulfenylation of imidazoheterocycles with sodium sulfinates under transition-metal-free conditions.

Generation of ArS-substituted flavone derivatives using aryl thiols as sulfenylating agents

The regioselective and metal-free sulfenylation of flavones was achieved under aerobic conditions with ammonium iodide as an inducer.

An odorless thia-Michael addition using Bunte salts as thiol surrogates

An efficient thia-Michael addition using odorless, easy to synthesis and handle Bunte salts as thiol surrogates is introduced.

Iodine-catalyzed regioselective thiolation of imidazo[1,2-a]pyridines using sulfonyl hydrazides as a thiol surrogate

Iodine-catalyzed regioselective sulfenylation of imidazo[1,2-a]pyridines via C(sp²)–H bond functionalization has been achieved using sulfonyl hydrazides as a thiol surrogate.

Unexpected TFA-catalyzed tandem reaction of benzo[d]oxazoles with 2-oxo-2-arylacetic acids: synthesis of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones and cephalandole A

TFA-catalyzed reaction of benzo[d]oxazoles with 2-oxo-2-arylacetic acids: synthesis of 3-aryl-2H-benzo[b][1,4]oxazin-2-ones and the natural product cephalandole A.

Cs2CO3 promoted direct C–H bond sulfenylation of imidazo[1,2-a]pyridines and related heteroarenes in ionic liquid

Cs₂CO₃-promoted sulfenylation of imidazo[1,2-a]pyridines in ionic liquid.

Amino acid and water-driven tunable green protocol to access S–S/C–S bonds via aerobic oxidative coupling and hydrothiolation

Arginine in conjunction with water has been employed as an effective and recyclable organocatalyst for oxidative coupling of thiophenols and hydrothiolation of alkynes.

K2S2O8/arenesulfinate: an unprecedented thiolating system enabling selective sulfenylation of indoles under metal-free conditions

Direct selective sulfenylation of indoles is disclosedviaan unprecedented deoxygenation of arylsulfonyl radical only under K₂S₂O₈/arenesulfinate system in CH₃CN/H₂O.