Aroylphenylacetylenes (I) reacted with ethyl and phenyl hydrazinecarboxylates (II) to give ω‐aroylacetophenone‐N‐ethoxycarbonyl‐(Vla‐f) and N‐phenoxycarbonyl‐(VIg‐l) hydrazones, respectively. When these were healed with acetic anhydride they were converted to 5‐aryl‐1‐ethoxycarbonyl‐and 1‐phenoxycarbonyl‐3‐phenylpyrazoles (VII), respectively, which on hydrolysis with rnethanolic potassium hydroxide gave the corresponding 5(3)aryl‐3(5)phenylpyrazoles (VIII). Reaction of the above acetylenic ketones with guanidine hydrochloride in the presence of sodium carbonate gave the corresponding 2‐amino‐6‐aryl‐4‐phenylpyrimidines (XII). Similarly, reaction of benzoylphenylacetylene with thiourea and with urea in the presence of sodium ethoxide gave rise to 2,4‐diphenylpyrimidine‐2‐thione (XVIII) and 2,4‐diphenyl‐2(1H)pyrimidin‐one (XV), respectively.

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1,3-Diaryl-2-propen-1-ones 1 reacted with thiourea in the presence of sodium ethoxide to give 4,6-diaryl-3,4-dihydropyrimidine-2(1H)thiones 5 which upon dehydrogenation with 3 mol of ethanolic sodium ethoxide yielded the corresponding 4,6-diarylpyrimidine-2(1H)thiones 9. The N-acetyl derivatives of the former thiones were prepared. Infrared, nuclear magnetic resonance, and ultraviolet spectral data of the above compounds were tabulated and discussed.

1,3‐Diaryl‐2‐propen‐1‐ones, I, reacted with guanidine hydrochloride (II) in the presence of 3 moles of sodium hydroxide to give the corresponding 2‐amino‐4,6‐diarylpyrimidines, III. The structure and configuration of the products are based on chemical and spectroscopic evidence. The protonation constants of these compounds (series A and series B) have been determined in 50 volume percent ethanol‐water medium. Excellent linear correlations are obtained when pKa values of the two series of 2‐amino‐4,6‐diarylpyrimidines, IIIa‐j and IIIk‐r, are plotted against the substituent constant, σx, and the polar substituent constant, σ* xC6H4, for substituted phenyl groups. The pKa values have also been correlated with the extended Hammett equation. The correlation follows the equations: Series A; pKa = 3.273 ‐ 0.820σI,X ‐ 0.662σR,X Series B; pKa = 3.169 ‐ 0.424σI,X ‐ 0.137σR,X

Aroylphenylacetylenes (I) reacted with thiourea and S‐benzylisothiourea to give 4,6‐diaryl‐pyrimidine‐2(1H)thiones (IV) and α‐aroyl‐β‐benzylmercaptostyrenes (X), respectively. Methyla‐tion and acetylation of the thiones (IV) gave the corresponding S‐methyl‐ (V) and S‐acetyl‐ (VI) derivatives, respectively. The oxidation of these thiones gave the corresponding disulfide derivatives (VII). Reaction of α‐aroyl‐β‐benzylmercaptostyrenes (X) with hydrazine hydrate and phenylhydrazine gave 3(5)‐aryl‐5(3)‐phenylpyrazoles (XI) and 3‐aryl‐1,5‐diphenylpyrazoles (XIII), respectively. Reaction of aroylphenylacetylenes (1) with N‐allylthiourea gave 1‐allyl‐4,6‐diaryl‐pyrimidine‐2‐thiones (XVI).