Oxidation of a mixture of diketene and a 1,1-diarylethene 1 with manganese(III) acetate dihydrate gave an equilibrium mixture of 5-hydroxy-2-pentanone 2 and a tetrahydrofuran-2-ol, which was subsequently dehydrated in glacial acetic acid to yield 4-penten-2-one 4 in good yield. A similar reaction in the presence of alcohols or amines afforded 2-alkoxy-2-methyltetrahydrofurans 5 or 3-acetyl-2-aminodihydrofurans 9 in moderate yields. Diketene reacted with manganese(III) acetate in the presence of nucleophiles, such as water and alcohols, to give a mixture of unconjugated manganese(III) enolate A and conjugated manganese(III) enolate B. Major products 4 and 5 were formed by the oxidation of the conjugated manganese(III) enolate B. Tetrahydrofurylideneacetates 3 and 7 derived from the unstable unconjugated enolate A were also obtained as minor products. The reaction pathways are discussed.

Formation of Tetrahydrofuran Derivatives and Acetonylation of Alkenes Using Carbon Radicals Derived from Manganese(III) Oxidation of Diketene

Manganese(III)-mediated facile synthesis of 3,4-dihydro-2(1H)-quinolinones: selectivity of the 6-endo and 5-exo cyclization

A series of [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (7-15) and the thiadiazine analogues 16-18 have been synthesized under microwave irradiation (MWI). All synthesized compounds are evaluated for their antiviral activity against the replication of HIV-1 and HIV-2 activity in MT-4. However, compounds 12 and 18 showed EC(50) = 2.11 and 1.97 mug/mL. The results suggest that these compounds can be considered as a new lead in the development of antiviral agents. Compounds 4-18 were tested in vitro against a panel of tumor cell lines. All compounds are inactive against all the tumor sub-lines, except 10 which exhibited activity against CD4(+) human acute T-lymphoblastic leukaemia of CC(50) = 64 muM.

In-vitro anti-HIV and antitumor activity of new 3,6-disubstituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles and thiadiazine analogues.

Manganese(III)-based dioxapropellane synthesis using tricarbonyl compounds

To discover new 1,2,4-triazole derivatives which may possess significant biological activities, we synthesized a series of novel 6-aryl-3-(D-galactopentitol-1-yl)- 7 H -1,2,4-triazolo[3,4- b ][1,3,4]thiadiazines and 4-(arylmethylidene)amino-5-(D-galacto- pentitol-1-yl)-3-mercapto-4 H -1,2,4-triazoles from 4-amino-3-(D-galactopentitol-1-yl)-5- mercapto-1,2,4-triazole. All the title compounds were characterized by elemental analysis, IR, 1 H- and 13 C-NMR. Plant growth-regulating activity tests showed that these compounds have remarkable effects on the growth of radish and wheat. Keywords: Galactose, 1,2,4-triazolo[3,4- b ]-1,3,4-thiadiazine, 4-(arylmethylidene)amino- 5-(D-galactopentitol-1-yl)-3-mercapto-4 H -1,2,4-triazole, NMR, plant growth-regulating. Introduction Various substituted 1,2,4-triazolo[3,4- b ]-1,3,4-thiadiazines and Schiff’s bases are associated with diverse pharmacological activities, such as analgesic, anthelmintic, antitubercular, plant growth regulating, antiviral, antifungal and anticancer properties [1-8]. 3-Substituted-4-amino-5-mercapto-

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Synthesis and biological activity of some novel derivatives of 4-amino-3-(D-galactopentitol-1-yl)-5-mercapto-1,2,4-triazole.

Synthesis of thiazole, oxazole and heterocyclic ring-substituted 1,2-dioxanes

Reaction of oligomethylene di(3-oxobutanoate) with 1,1-disubstituted alkenes and molecular oxygen in the presence of manganese (ii and/or iii) acetate

Manganese(III)‐mediated intermolecular cyclization reactions of alkenes and active methylene compounds

Syntheses of 4‐(2‐hydroperoxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles, 4‐(2‐hydroxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles and the related compounds

The reactions of 1,1-disubstituted ethenes with 2,4-pentanedione in the presence of manganese(III) acetate and atmospheric oxygen yielded 4-acetyl-6,6-diaryl-3-methyl-1,2-dioxan-3-ols. The latter gave 4-(2-hydroperoxy-2,2-diarylemyl)-3,5-dimethylpyrazoles by the reaction with hydrazines in methanol-acetic acid (1:1 v/v) at 50° in 15-77% yields, or 4-(2-hydroxy-2,2-diarylethyl)-3,5-dimethylpyrazoles by the reaction with hydrazines in methanol in 2-78% yields. The acid-catalyzed reaction of 4-(2-hydroperoxy-2,2-diarylethyl)-3,5-dimethylpyrazoles yielded 4-(aroylmethyl)-3,5-dimethylpyrazoles (15-55%) and 4-(2,2-diarylethenyl)-3,5-dimethylpyrazoles (9-29%).

Jie Ouyang

Papers

Synthesis of thiazole, oxazole and heterocyclic ring-substituted 1,2-dioxanes

Reaction of oligomethylene di(3-oxobutanoate) with 1,1-disubstituted alkenes and molecular oxygen in the presence of manganese (ii and/or iii) acetate

Manganese(III)‐mediated intermolecular cyclization reactions of alkenes and active methylene compounds

Syntheses of 4‐(2‐hydroperoxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles, 4‐(2‐hydroxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles and the related compounds

Syntheses of 4‐(2‐Hydroperoxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles, 4‐(2‐Hydroxy‐2,2‐diarylethyl)‐3,5‐dimethylpyrazoles and the Related Compounds.