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5-Benzoyl-4-methylpyrimidines 4a,b and 5-acetyl-4-phenylpyrimidines 5a,b reacted with hydrazines in alcoholic acidic medium to give respectively 4-acetyl-3-phenylpyrazoles 7, 9 and 10 and 4-benzoyl-3-methylpyrazoles 6, 8 and 11. In the reaction with phenylhydrazine, 5-benzoyl-4-methyl-2-methylthiopyrimidine (4a) led exclusively to 4-acetyl-1,3-diphenylpyrazole (10) as 5-acetyl4-phenyl-2-methylthiopyrimidine (5a) led to 4-benzoyl-3-methyl-1-phenylpyrazole (11) via the initial formation of phenylhydrazones of pyrimidines 4a and 5a. However, 5-benzoyl-4-methyl-2-phenylpyrimidine (4b) and 5-acetyl-2,4-diphenylpyrimidine (5b) reacted with phenylhydrazine to afford, each of them, a mixture of two isomeric pyrazoles. The mechanism of these ring contraction reactions is discussed.

Triacetylmethane (1) reacts with amidinohydrazines in acidic medium to afford 4-acetyl-3,5-dimethylpyrazole amidinohydrazone derivatives 2,4. However, a similar reaction of 1 with thiosemicarbazide or semicarbazide led mainly to 3,5-dimethylpyrazole (6). The great propensity of 1 to hydrolysis accounts for this last transformation, as well as for the fact that with guanidine it led to 2-amino-4,6-dimethylpyrimidine (10) and with S-methylisothiourea it provided the unexpected 2-amino-4-methyl-6-methylthio-1,3,5-triazine (11).

Triformylmethane (1) reacted with benzamidine, guanidine and S-methyl- isothiourea to give the corresponding 2-substituted pyrimidines-5-car- boxaldehydes. However, reactions of (1) with acetamidine (or formami- dine) and phenylbiguanide gave the unexpected 1-aminoethylene-2,2-di- carboxaldehyde (5) and 2-amino-4-anilino-1,3,5-triazine (9), respecti- vely

The ring contraction of 4-ammo-1H-1,5-benzodiazepine-3-carbonitrile hydrochloride 1 and ethyl 4-amino-1H-1,5-benzodiazepine-3-carboxylate hydrochloride 2 with aromatic primary amines into benzimidazole derivatives 3 and 4 was readily accomplished by heating in methanol. Benzodiazepine 1 also reacted with methylamine and ethylamine at about 40° to give ring-opened amine adducts 7 which were recyclized to 1 with hydrochloric acid.

We have found previously that two 5-acetyl-4-methylpyrimidines could be transformed by aminoguanidine hydrochloride into 4-acetyl-1-amidino-3-methylpyrazolyl amidinohydrazone dihydrochloride. This reaction beside the fact that it led to a molecule closely related to the antitumor drug M.G.B.G. pointed out to a new possibility of ring contraction of pyrimidines into pyrazoles. We attempted therefore to study the possibility of extending this transformation to other substituted hydrazines and to define more accurately the conditions of this reaction as well as to prepare new potential anticancer drugs.

Seules parmi les produits isomeres possibles les N(2),N'(2′) α,ω alcanediylbis(amino-2 pyrimidines) sont formees lorsque des polymethylenebisguanidines sont condensees avec l'ethoxymethylenemalonate d'ethyle, la methyl-3 chromone, la flavone, l'acetylacetaldehyde dimethylacetal, et l'acetyl-3 ethyl-2 benzofuranne. N(2), N′(2′)-αω-Alkandiylbis(2-aminopyrimidines) are the sole products obtained by condensation of several polymethylene bisguanidines on ethyl ethoxymethylenemalonate, 3-methlchromone, flavone, acetylacetone, acetylacetaldehyde dimethylacetal and 3-acetyl-2-ethylbenzofuran.

La guanidine transforme: la formyl-3 chromone en un melange d'amino-2 (hydroxy-2 benzoyl)-5 pyrimidine et d'amino-2 hydroxy-5 5H(1) benzopyranno[4–3-d]pyrimidine; le diacetate de methylidyne-3 chromone en amino-2 hydroxy-5 5H(1) benzopyranno[4,3-d]pyrimidine, et l'ox-ime de la formyl-3 chromone en amino-2 5H(1)benzopyranno[4,3-d]pyrimidinone-5. La thiouree, l'acetamidine et la nitroguanidine sont egalement capables d'engendrer des pyrimidines du měme type avec la formyl-3 chromone, le diacetate de methylidyne-3 chromone ou la (dioxolanne-1,3 yl-2)-3 chromone. Guanidine transforms the following: (a) 3-formylchromone into a mixture of 2-amino-5-(2-hydroxybenzoyl)pyrimidine and 2-amino-5H-[1]-benzopyrano[4,3-d]pyrimidine; (b) the diacetate of 3-methylidyne-chromone into 2-amino-5-hydroxy-5H-[1]benzopyrano[4,3-d]pyrimidine; and (c) the oxime of 3-formylchromone into 2-amino-5H-[1]benzopyrano-[4,3-d]pyrimidin-5-one. Thiourea, acetamidine and nitroguanidine can also generate pyrimidines of the same type with 3-formylchromone, the diacetate of 3-methylidynechromone or 3-(1,3-dioxolan)chromone.