Electrochemical and direct C-H methylthiolation of electron-rich aromatics
The electrochemical-induced C-H methylthiolation of electron-rich aromatics has been accomplished via a three component cross-coupling strategy. Potassium thiocyanate (KSCN) as both the supporting electrolyte and sulfur source and methanol as the methylation reagent are used. This protocol is versatile for various (hetero)aromatic compounds such as aniline, anisole and indole. The reaction proceeds under mild conditions without any metal catalyst, exogenous oxidant and highly toxic sulfur reagent. Importantly, such an electrochemical-induced methylthiolated reaction could be easily scaled up with good efficiency.
Highly regioselective para-methylthiolation/bridging methylenation of arylamines promoted by NH4I
Aryl methyl thioethers and methylene-bridged arylamines were synthesized via highly regioselective para-methylthiolation/bridging methylenation of arylamines using DMSO as the methylthio or methylene source in the presence of NH4I under metal-free conditions. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields.
Xu, Yinfeng,Cong, Tiantian,Liu, Ping,Sun, Peipei
supporting information
p. 9742 - 9745
(2015/10/05)
Formation of Sommelet-Hauser-Type Products, 2-Aminoarylmethyl Sulphides, and Nitrenium Ion Products, 2- and 4-Aminoaryl Sulphides, via an N-Arylazasulphonium Salt
Reactions of a salt (1) formed at -60 deg C from trifluoroacetic anhydride and dimethyl sulphoxide (DMSO) with primary and secondary arylamines gave 2-aminoarylmethyl sulphides (6), (6') and (12) by a Sommelet-Hauser rearrangement of an ylide (5) formed by loss of a methyl proton of an N-arylazasulphonium salt (3) in the absence of base.The use of ethyl methyl sulphoxide instead of DMSO afforded a similar product (19b) by loss of not the ethyl but the methyl proton.However, the use of diethyl sulphoxide merely caused loss of an ethyl group from the N-arylazasulphonium salt to yield ethanesulphenanilide (20).The reaction of (1) with N-phenyl-1-naphthylamine gave mainly aminoaryl sulphides (13) and (14) via an arylnitrenium ion from the N-arylazasulphonium salt.In fact, the reaction of dimethyl sulphide (DMS) with arylnitrenium ions formed in the acid decomposition of aryl azides gave no Sommelet-Hauser-type products but 2- and 4-aminoaryl sulphides (22), (22') and (23).We also discuss the possibility of the N-arylazasulphonium salt being formed by reaction of the arylnitrenium ion with DMS.