Novel 3-(4-piperidinylthio)-1H-indoles as potent nonopioid orally active central analgesics

Graphene oxide mediated thiolation of indoles in water: a green and sustainable approach to synthesize 3-sulfenylindoles

Graphene oxide, a green and recyclable catalyst, was developed to synthesize 3-sulfenylindoles in water.

Metal- and phosphine-free electrophilic vicinal chloro-alkylthiolation and trifluoromethylthiolation of indoles using sodium sulfinate in the presence of triphosgene

Efficient chloro-alkylthiolation and trifluoromethylthiolation of indole derivatives were developed.

DMSO as oxidant and sulfenylating agent for metal-free oxidation and methylthiolation of alcohol-containing indoles

A new methylthiolation protocol was successfully established for the synthesis of substituted indoles bearing 3-methylthioether moiety, in which new C–S bond and C=O bond were formed using dimethyl sulfoxide as the sulfur source under mild conditions.

A practical regioselective synthesis of alkylthio- or arylthioindoles without the use of smelly compounds such as thiols

A convenient method for the synthesis of 3-methylthioindoles has been established which does not use smelly compounds such as thiol derivatives. The method, which introduces an alkyl- or arylthio-group into the C(3)-position of the indole skeleton, was extended to the direct introduction of a methylthio or bromo group at the C(2)-position using 3-methylthioindoles. No dimerization occurred, and the reaction mechanism was confirmed. The products have the partial structure of potent anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) bromomethylthioindoles (MC 5-8) isolated from marine algae. Furthermore, this reaction could be applied to the synthesis of 3,3-diindolyl thioether which is a core structure of Echinosulfone A.

Regioselective Copper-catalyzed C-N and C-S Bond Formation using Amines, Thiols and Halobenzoic Acids

A regioselective method for highly efficient C-N and C-S bond formation with 2-halobenzoic acids is described. The Cu/Cu(2)O-catalyzed reaction is carried out in 2-ethoxyethanol or ethylene glycol diethyl ether and does not require the use of strong base or other additives. This procedure eliminates the need for acid protection, tolerates a wide range of functional groups and provides aromatic and aliphatic amines and sulfides in 81 to 99% yield.

Vanadium-catalyzed sulfenylation of indoles and 2-naphthols with thiols under molecular oxygen

Vanadium oxyacetylacetonate [VO(acac)(2)] works as a catalyst for the direct synthesis of 3-sulfanylindoles from indoles and thiols under an atmospheric pressure of molecular oxygen as a reoxidant. For example, the reaction of 2-phenylindole with benzenethiol in the presence of a catalytic amount of VO(acac)(2), potassium iodide, and 2,6-di-tert-butyl-p-cresol in chlorobenzene under molecular oxygen proceeds to afford 2-phenyl-3-(phenylsulfanyl)indole in 86% yield. This catalytic system can also be applied to 2-naphthols instead of indoles to give the corresponding 1-sulfanyl-2-naphthols in up to 57% yield.