Preparation and chemistry of the Diels-Alder adducts of levopimaric acid and activated thiocarbonyl dienophiles

Abstract

The reactions of levopimaric acid (1) with the activated dienophiles methyl cyanodithioformate (2) and jV-benzoyl-N-phenylcyanothioformamide (3) are reported. The resulting Diels-Alder adducts were then subjected to various reaction conditions, including acid and/or base hydrolysis, permanganate oxidation, and catalytic hydrogenation, where applicable.After reinvestigating the fundamental chemistry of the especially interested in a group of analogous heteroatomic model formaldehyde-levopimaric acid adduct,11 became dienophiles, the activated thiocarbonyls. First of all, these

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

“…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.…”

Synthesis, characterization, and derivatization of some novel types of fluorinated mono- and bis-imidazolidineiminothiones with antitumor, antiviral, antibacterial, and antifungal activities

“…Thus, commercial isocyanates 5a-g with various aromatic substituents (p-tolyl, p-methoxyphenyl, p-thiomethylphenyl, benzyl, p-chlorophenyl, 3,5-dichlorophenyl, and 2,4,5-trichlorophenyl) were reacted with an equimolar amount of p-fluorocyanothioformanilide (4) in ether in the presence of a few drops of triethylamine as a catalyst to furnish the corresponding 5-imino-4-thioxo-2-imidazolidinones 6a-g as shown in Scheme 2. p-Fluorocyanothioformanilide (4) was prepared by treating an ethanolic solution of commercial 4-fluorophenyl isothiocyanate with an aqueous solution of KCN according to literature protocols [10][11][12][13][14][15][16][17][18][19]. The ring closing reaction proceeded by attack of the nitrogen atom of the cyanothioformanilide onto the isocyanate carbon, where the ensuing annulation proceeds by attack of the resulting nitrogen anion onto the electrophilic nitrile group.…”

“…The products were obtained as pure crystalline solids in 75-85% yields and were fully characterized by standard spectroscopic and analytical methods (see Experimental and Supplementary material sections). The arylcyanothioformanilides 8a-g were prepared from either commercial arylisothiocyanates and KCN according to literature protocols [10][11][12][13][14][15][16][17][18][19] or through the preparation of dithiocarbamates from aromatic amines, followed by conversion to the corresponding isothiocyanates and the subsequent cyanation to afford the desired aryl cyanothioformanilides. Hydrolysis of 10a-e with dilute HCl in boiling ethanol afforded diones 11a-e as crystalline solids.…”

“…These have been earlier prepared by treating N-aryl isothiocyanates with cyanide [10][11][12][13][14][15][16][17][18][19] and by other classical methods [20]. Recent approaches have employed environmentally-friendly N-arylimino-1,2,3-dithiazoles which transform readily to the corresponding cyanothioformanilides under various conditions [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

“…Recent approaches have employed environmentally-friendly N-arylimino-1,2,3-dithiazoles which transform readily to the corresponding cyanothioformanilides under various conditions [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. N-Arylcyanothioformanilides have found wide utility in organic synthesis [11,15,[37][38][39][40][41][42][43] and we have used them to prepare various heterocycles with promising pharmacological properties. Such reagents are ambident nucleophiles as reflected by their existence as tautomeric mixtures [44,45], and thus may react at the sulfur or nitrogen atom.…”