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The reactions of 1,1-disubstituted ethenes with barbituric acid and its derivatives in the presence of manganese(II) acetate and air yielded 5,5-bis(2-hydroperoxyalkyl)barbituric acids 3aa-ac and 3ba-ja in 62-99% yields. The structure of 3ab was determined by X-ray crystallography. The reaction of la and 2a was also effected by manganese(III) acetate (95%) and metallic manganese (92%), but in poor yield by cerium(IV) ammonium nitrate (50%). Treatment of 5,5-bis(2-hydroperoxy-2.2-diphenylethyl)-l,3-dimethylbarbituric acid (3aa) with perchloric acid gave 5,5-bis(benzoylmethyl)-1.3-dimethylbarbituric acid ( 6) and 5-(2-benzoylmethyl)-l,3-dimethyl-5-(2,2-diphenylethenyl)barbituric acid (7), in which phenyl migration took place. Reduction of 3aa with zinc powder in acetic acid or with triphenylphosphine in diethyl ether yielded 5,5-bis(2-hydroxy-2,2-diphenylethyI)-1.3-dimethylbarbituric acid (10), which was dehydrated to give a spirotetrahydropyran 11.

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The reactions of 1,1-diphenylethene, 1,1-bis(4-chlorophenyl)ethene, 1,1-bis(4-methoxyphenyl)ethene, 1,1-bis(4-methylphenyl)ethene, 1,1-bis(4-fluorophenyl)ethene, styrene, 1-octene, cyclohexene, and cyclooctene with tris(2,4-pentanedionato)manganese(III) ([Mn(acac)3]) in acetic acid at room temperature give 4-acetyl-3-methyl-1,2-dioxan-3-ol in 8–92% yields, together with 3-acetyl-4-hydroxy-3-hexene-2,5-dione. The similar reactions of 1,1-diphenylethene with 2,4-pentanedione, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione, 1-phenyl-1,3-butanedione, acetoacetanilide, and 1,3-cyclohexanedione in the presence of manganese(III) acetate also give the corresponding cyclic peroxide in good to moderate yields. The mechanisms of manganese(III)-induced 1,2-dioxane ring formation and concomitant radical side reaction are discussed.

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The synthesis and coronary vasodilating and antihypertensive activities of 1,2,4-triazolo[1,5-a]pyrimidines fused to pyrrole, thiophene, pyran, pyridine, and pyridazine are described. Among these compounds, 8-tert-butyl-7,8-dihydro-5-methyl-6H-pyrrolo[3,2-e][1,2,4]triazolo[1,5-a]pyrimidine (23) was found to be the most promising potential cardiovascular agent, having been shown to be more potent in coronary vasodilating activity than trapidil [7-diethylamino)-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine] and approximately equipotent to guanethidine sulfate in antihypertensive activity.