Reaction Using Sulfinyl-, Sulfonyl-, and Phosphinoyl-2-propanones

It was found that the 1,3-dicarbonyl compounds were effective for use in the synthesis of 1,2-dioxan-3-ols. In order to pioneer its synthetic utility, the endoperoxidation of alkenes using sulfinyl-, sulfonyl-, and phosphinoyl-substituted 2-propanones, which are the congener of the 1,3-dicarbonyl


OHa:OHe R = Aryl (76-58%) ca. 80:20 R = Et (51%) 70:30

OHa:OHe R = Aryl (76-58%) ca. 80:20 R = Et (51%) 70:30




Ph H

Scheme 13 Synthesis of 1,2-dioxan-3-ols using sulfinyl-, sulfonyl-, and phosphinoyl-2-propanones compounds, were investigated. The reaction at room temperature (23 °C) practically did not take place, but needed a higher reaction temperature (32-48 °C) for the reaction to progress. The reaction of phenylsulfinyl-2-propanone with alkenes was carried out at 32 ° C in the presence of manganese(III) acetate to give the corresponding 4-(phenylsulfinyl)-1,2-dioxan-3-ols together with a small amount of benzophenones and glycol monoacetates (Scheme 13) [84]. A similar reaction at 48 °C using phenylsulfonyl-2-propanone, (4-methylphenyl)sulfonyl-2-propanone, and dimethoxyphosphinoyl-2-propanone also afforded the corresponding diox-anes, along with a small amount of by-products.

The sulfinyl- and sulfonyl-substituted dioxanes were obtained as a mixture of two stereoisomers. The C-3 hydroxyl group of the major stereoisomer was axially oriented, and the sulfinyl, sulfonyl, and phosphinoyl groups at the C-4 position were placed equatorially, based on the 1H and 13C NMR spectra [84].

Reaction Using Acylacetonitrile Building Blocks

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 4ff-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 compounds in one step [73,75,77,80,101-

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