Alkenes acetic acid, manganese®! acetate

A hydroxy and an arylthio group can be added to a double bond by treatment with an aryl disulfide and lead tetraacetate in the presence of trifluoroacetic acid." Manganese and copper acetates have been used instead of Pb(OAc)4. ° Addition of the groups OH and RSO has been achieved by treatment of alkenes with O2 and a thiol (RSH)." Two RS groups were added, to give vie- dithiols, by treatment of the alkene with a disulfide RSSR and Bp3-etherate."° This reaction has been carried... 

The preparation and immediate use of manganese(III) azide species generated slowly in situ by refluxing manganese(III) acetate and sodium azide in acetic acid in presence of alkene reaction substrates to prepare 1,2-diazidoalkanes avoids the need to isolate manganese(III) azide which has a high probability of explosive instability [1]. The (II) azide is known [20260-90-6], isolable, detonable and has been patented as a power source for lasers [2],... 

Polycyclic y-lactones. An intramolecular version of the formation of y-lactones by reaction of an alkene with acetic acid and manganese(HI) acetate (1) (6, 355-356) provides a general route to polycyclic y-lactones. Thus the unsaturated p-keto acid 2 cyclizes to the ds-bicyclic y-lactone 3 when warmed in acetic acid with 1 (1.3 equiv.)2... 

In the presence of manganese triacetate and the azide anion in refluxing acetic acid alkenes are converted to 1,2-diazides in satisfactory yield, most probably through a ligand transfer-oxidation mechanism74. 

Manganic acetate (manganese triacetate), Mn(OCOCH3)3, is prepared by refluxing a solution of manganese acetate tetrahydrate in acetic acid with potassium permanganate [S03]. This oxidant hydroxylates ben-zylic methylene groups [416] and forms lactones from terminal alkenes [803, 804] (see equation 88). 

In the presence of dioxygen, the carbon radical R- produced by reactions (201) and (202) ar transformed into alkylperoxy radicals ROO, reacts with Co or Mn species to regenerate th Co " or Mn " oxidants, and produce primary oxygenated products (alcohol, carbonyl compounds which can be further oxidized to carboxylic acids. This constitutes the basis of several Industrie processes such as the manganese-catalyzed oxidation of n-alkenes to fatty acids, and the cobal catalyzed oxidation of butane (or naphtha) to acetic acid, cyclohexane to cyclohexanol-on mixture, and methyl aromatic compounds (toluene, xylene) to the corresponding aromatic monc or di-carboxylic acids. ... 

Manganese(III)-mediated radical reactions have become a valuable method for the formation of carbon-carbon bonds over the past thirty years since the oxidative addition of acetic acid (1) to alkenes to give y-butyrolactones 6 (Scheme 1) was first reported by Heiba and Dessau [1] and Bush and Finkbeiner [2] in 1968. This method differs from most radical reactions in that it is carried out under oxidative, rather than reductive, conditions leading to more highly functionalized products from simple precursors. Mn(III)-based oxidative free-radical cyclizations have been extensively developed since they were first reported in 1984-1985 [3-5] and extended to tandem, triple and quadruple cyclizations. Since these additions and cyclizations have been exhaustively reviewed recently [6-11], this chapter will present an overview with an emphasis on the recent literature. 

Manganese(III) can oxidize carbonyl compounds and nitroalkanes to carboxy-methyl and nitromethyl radicals [186]. With Mn(III) as mediator, a tandem reaction consisting of an intermolecular radical addition followed by an intramolecular electrophilic aromatic substitution can be accomplished [186, 187). Further Mn(III)-mediated anodic additions of 1,3-dicarbonyl and l-keto-3-nitroalkyl compounds to alkenes and alkynes are reported in [110, 111, 188). Sorbic acid precursors have been obtained in larger scale and high current efficiency by a Mn(III)-mediated oxidation of acetic acid acetic anhydride in the presence of butadiene [189]. Also the nitromethylation of benzene can be performed in 78% yield with Mn(III) as electrocatalyst [190]. A N03 radical, generated by oxidation of a nitrate anion, can induce the 1,4-addition of aldehydes to activated olefins. NOj abstracts a hydrogen from the aldehyde to form an acyl radical, which undergoes addition to the olefin to afford a 1,4-diketone in 34-58% yield [191]. 

The system Ru(III)-EDTA catalyzes the oxidation of cyclohexane by molecular oxygen [26]. In the presence of manganese(II) acetate and molecular oxygen, alkenes and active methylene compounds react to yield cyclic peroxides [27]. a-Substituted cycloalkanones are oxidized to oxo acids by the copper(II) nitrate-dioxygen-acetic acid-water system [28a] ... 

Oxidative radical cyclization sequences have also been used to generate 1,2-fused indoles. Treatment of amides 152 and 154 with dimethyl methylmalonate in the presence of manganese(III) acetate and sodium acetate in acetic acid, gave the expected cyclized product in 63% and 40%, respectively [97]. The proposed mechanistic sequence involves the intermolecular addition of the dimethyl methylmalonate radical to the tethered exocyclic alkene followed by cyclization and finally rearomatization. Byers and coworkers also achieved a similar cyclization on the C-2 position of the indole when a 3-acylindole was subjected to these oxidative cyclization conditions. 

Scheme 1 Typical oxidation of alkenes with manganese(lll) acetate in acetic acid...

Scheme 4 Reaction of alkenes with tris(2,4-pentanedionato)manganese(III) in acetic acid at room temperature in air...

Since it is known that a-protons of the acylacetonitriles are more acidic than those of the methyl ketones, it was logical to use the acylacetonitrile building blocks during the first stage of the aldol-like condensation for the synthesis of heterocyclic compounds such as the 4H-pyran, 2-pyridone, and furan derivatives [85-95]. Therefore, it was expected that acylacetonitriles would be oxidized by manganese(III) acetate in a similar manner to the oxidation of a-cyanoacetic acid [65,96-99] and 1,3-dicarbonyl compounds [100] to give acylcyanomethyl radicals, CH(COR)CN, which would attack the alkenic double bonds to produce heterocyclic compoimds in one step [73,75,77,80,101-... 

A similar reaction of various alkenes with 2,4-pyrrolidinediones was carried out in acetic acid at room temperature under a dry air stream in the presence of manganese(Ill) acetate to give the l-hydroxy-8-aza-2,3-dioxabicyclo[4.3.0]nonan-7-ones in good to quantitative yields [127,... 

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