α-Thioxothioamides: A Formal [4+1] Cycloaddition Reaction with Isocyanides and Diisocyanides and its Application to a New Straightforward Formation of Extended Tetrathiafulvalenes

Abstract

A number of 2‐(alkylimino) and 2‐(arylimino)‐1,3‐dithioles (aza DTFs) bearing push‐pull substituents have been prepared under mild conditions according to the title procedure. This novel strategy relies upon the fact that the use of conjugated diisocyanides allows an effective synthesis of new extended tetrathiafulvalenes (TTFs). The two dithiole moieties are linked by a conjugated framework that incorporates a phenyl, biphenyl or azobiphenyl group. High and low temperature measurements are required in order to understand the complex 1H and 13C NMR spectra of the prepared mono‐, bis‐ and tris‐(1,3‐dithiole) derivatives. Their electrochemical oxidations are also described.

Synthesis and Anticancer Activity Comparison of Phenylalkyl Isoselenocyanates with Corresponding Naturally Occurring and Synthetic Isothiocyanates

“…Several modifications30 in the procedure have been made since then to improve yields and avoid polymerization31 of intermediate compounds 29, 32. We have used the method of Fernandez-Bolanos et al 33.…”

“…The first synthesis of isoselenocyanates was reported by Barton et al starting from the corresponding formamides. Several modifications in the procedure have been made since then to improve yields and avoid polymerization of intermediate compounds. , We have used the method of Fernandez-Bolanos et al, which conveniently uses solid triphosgene, instead of phosgene, in a one-pot dehydration of the formamides in refluxing dichloromethane (Scheme ). The synthetic strategy involved the formylation of phenylalkylamines, followed by treatment with triphosgene and selenium powder in the presence of triethylamine to furnish the desired phenylalkyl isoselenocyanates ( 2 ) in good yields.…”

Isocyanide based [4+1] cycloaddition reactions: an indispensable tool in multi-component reactions (MCRs)

“…The authors synthesized unsymmetrical aza-1,3-dithiafulvenes 149 (aza-DTFs) via formal [4+1] cycloaddition of isocyanide 1 and a-thioxothioamides 148 in 14-85% yields (Scheme 48). 60 Mechanistically, the initial attack of isocyanide 1 on one of the resonating structures of a-thioxothioamides 148, concomitantly produced the transient zwitterionic nitrilium intermediate I, followed by ring-closure to provide aza-1,3-dithiafulvenes (aza-DTFs) analogues 149. Moreover, the rate of reaction was significantly influenced by the electronic effect of substituents present on the aryl nucleus of a-thioxothioamides.…”

t-Butyl Isocyanide

“…48 The reaction also works with dimethyl tetrathiooxalate, which can be generated by in situ electrochemical reduction of CS 2 , to give bis(methylthio)-2-imino-1,3-dithiole (eq 37). 48 The reaction also works with dimethyl tetrathiooxalate, which can be generated by in situ electrochemical reduction of CS 2 , to give bis(methylthio)-2-imino-1,3-dithiole (eq 37).…”