Syntheses of some novel imidazolidinethiones and condensed imidazoles containing arylazo moieties starting from cyanothioformamides

Abstract

Cyclocondensation of cyanothioformamides (1) with arylhydrazonomalononitriles (2)

Synthesis and Biological Evaluation of Bis‐Imidazolidineiminothiones: A Comparative Study

“…Thus, one equivalent of commercial hexamethylene diisocyanate ( 5 ) was reacted with two equimolar amounts of cyanothioformanilides 1a – g containing various aromatic substituents ( p ‐tolyl, p ‐methoxyphenyl, p ‐chlorophenyl, p ‐bromophenyl, p ‐iodophenyl, and 3,5‐dichlorophenyl) in ether, followed by the addition of a few drops of triethylamine as a catalyst to furnish the corresponding 3,3′‐(hexane‐1,6‐diyl)bis(1‐aryl‐4‐imino‐5‐thioxoimidazolidin‐2‐ones 6a – g as shown in Scheme . Arylcyanothioformanilides 1a – g were prepared by either treating an ethanolic solution of the requisite commercial arylisothiocyanate with an aqueous solution of KCN according to literature protocols or through the preparation of dithiocarbamates from aromatic amines, followed by conversion to the corresponding isothiocyanates, and a subsequent cyanation to afford the desired aryl cyanothioformanilides. The annulation reaction proceeded smoothly and cleanly by attack of the nitrogen atom of the arylcyanothioformanilide onto the isocyanate carbons of hexamethylene diisocyanate, where the ensuing ring closing step proceeded by attack of the resulting nitrogen anion onto the electrophilic nitrile group.…”

“…For the preparation of the known cyanothioformanilides 1a – g , see . Also see and references therein.…”

“…Interestingly, aromatic cyanothioformanilides are themselves bioactive and have been reported to exhibit a wide spectrum of bioactivity . Several classical methods as well as more recent eco‐friendly protocols have been reported in the literature for the preparation of such compounds.…”

“…N ‐Arylcyanothioformanilides are ambident nucleophiles and may react via the sulfur or nitrogen atom , with the nitrile group serving as an electrophilic tether that may participate in subsequent transformations. These inherent features have been employed to design several “one‐pot” annulation reactions to produce various heterocyclic cores .…”

Imidazoline‐4‐thiones from cyanothioformamides and aldehyde imines: Formation, aromatization, and acetylation

“…Similarly, the Asinger group has reported the formation of imidazolethiols 2 from α‐oxothioamides and aldimines [8]. Recently, we have reported the synthesis of oxazolidines 4 from cyanothioformamides 3 and aldehydes or ketones [9] as part of our study on heterocyclic ring‐closure reactions [10–16] and now envisaged that cyanothioformamides 3 and N ‐unsubstituted aldimines should give products of type 2 , though with a 5‐amino group as additional feature which may assist in free‐radical trapping. However, the position of the tautomeric equilibrium in the probable cyclization products 6 between iminothiones 6A , aminothiones 6B , and aminothiols 6C is a priori open (Scheme ).…”