Addition reactions of heterocyclic compounds. Part 74. Products from dimethyl acetylenedicarboxylate with thiourea, thioamide, and guanidine derivatives

Regioselective synthesis, structure and behavior in solutions of novel phosphorylated thiazolidin‐4‐ones

“…Condensation of thioureas with dimethyl acetylenedicarboxylate (DMAD) is known to be a convenient route to pharmacologically active 2-imino-5-methoxycarbonylthiazolidin-4-ones [1][2][3][4][5][6][7]. Recently malonothioamide derivatives were found to undergo a similar heterocyclization resulting in substituted 2,5-bis(substituted methylidene)-thiazolidine-4-ones 1 usually as a mixture of Z,Z and E,Z isomers (see Scheme 1) [8,9].…”

Synthesis of 2-iminoimidazolidin-4-one derivatives by cyclization of 2-aryl-1-(4,6-dimethylpyrimidin-2-yl)guanidines with ethyl bromoacetate, dimethyl acetylenedicarboxylate, and maleic anhydride

“…These compounds can undergo keto enol tautomerism. The fact that the 1 H NMR spectrum in DMSO d 6 shows a singlet at δ 4.44 is indicative of the almost complete shift of the equilibrium toward the ketone form.…”

“…Based on this fact, it was concluded that DMAD reacts with unsubstituted guanidine to give the five membered heterocycle. 6 The position of the signal for this proton (δ 5.54-5.71) in the spectra of the reaction products sug gests that the reactions afford one of 12 possible imid azolidinones. The ultimate choice was made based on the NOESY data.…”

Reactions of ?-acetylenic ketones with n-3-amidinothioureas. 1. Synthesis and properties of new derivatives of 1,3-thiazine

“…Condensation of thioamides and thiourea with α,β-unsaturated ketones, esters of propiolic and acetylenedicarboxylic acids [4][5][6][7] is one of the basic methods for the preparation of substituted 1,3-thiazines which are used as fungicides, pharmaceuticals, and vulcanizing agents [8]. Moreover guanidine is involved in the classical heterocyclization reaction which leads to biologically important derivatives of pyrimidine, and guanidine is a structural fragment of nucleic acids and streptomycin.…”