Trioxane ketones

For example, such a photooxygenation of alcohols 569 lead to unsaturated alcohol-hydroperoxides 570, which react with ketones and aldehydes to give 1,2,4-trioxanes 571 characterized by a-styryl-substituents at the 6-position (Scheme Geraniol... 

Singh and coworkers have carried ont a large amonnt of work on the synthesis of sprro 1,2,4-trioxanes by employing the ene reaction of singlet oxygen with substituted ally lie alcohols The resulting hydroperoxy alcohols 86a can be condensed with a variety of different carbonyl compounds inclnding cyclic ketones (Scheme 33). Some of these trioxanes 86b have excellent in vivo activity (see Table 1). 

Aerobic Co(II) catalysed hydroperoxysiiyiation of allylic alcohols provides silyl peroxides that can be condensed with ketones to produce 1,2,4-trioxanes or 1,2,4-trioxepanes by a simple one-pot procedure (Scheme 35A). A recent improvement in the use of Co(acac)2 is the use of Co(thd)2 (thd = bis (2,2,6,6-tetramethyl-3,5-heptanedionato)). This more reactive catalyst allows cyclic allylic alcohols to be oxygenated and the resulting peroxysilyl alcohol can be transformed to spiro trioxanes, some of which have potent in vitro antimalarial activity (Scheme 35B). For example, compound 87 expresses activity around 20 nM (artemisinin = 10 nM). 

Aminals, conveniently prepared in low cost by condensation of a carbamate, an azole and either a ketone, paraformaldehyde, or trioxane in the presence of a Lewis acid and/or a Cu(ii) salt were useful as intermediates for photographic couplers and organic synthesis. A number of examples incorporating pyrazolotriazole moieties have been described <1995JPP07133259>. 

Trioxacycloalkanes. 1.2,4-Trioxanes (1), X = OR4 R4 and R4 = alkylene) are generally prepared by the interaction of aldehydes with zwitterionic intermediates made from reaction of singlet oxygen with olefins. They can also be prepared by catalyzed reaction of ketones or... 

See CYCLIC PEROXIDES, KETONE PEROXIDES Lead, Trioxane... 

Ozonolysis of the model compounds (372a,b) followed by treatment with amberlite 15 in the presence of an aldehyde or a ketone yielded several pyrano-1,2,4-trioxanes. Reaction of compounds (372a,b) in the presence of acetone delivered the corresponding trioxanes (44) and (20) in yields of 25% and 32%, respectively. An analogous reaction of compound (372a) in the presence of acetaldehyde gave the trioxane (44) (23%) <90CC1487>. 

Trioxanes 726 (Z = 0) are trimers of aldehydes or ketones formed by acid-catalyzed condensations of the monomers. 1,3,5-Trithiane 726 (Z = S) is prepared by passing H2S through formaldehyde and hydrochloric acid <1943OSC(2)610>. The reaction of formaldehyde and H2S with amines affords the corresponding thiadiazines 727 (Scheme 311) <2003RCB1817, CHEC-III(9.09.9.3)511>. 

Wessl6n has investigated the acid-catalyzed reactions of trioxane with methyl alkyl ketones to give di-oxanes representative data are shown in equation (54) and Table 4. These data show a strong preference for reaction at a more substituted position. Indeed, the examples presented where reaction must occur at a methyl group (acetone and pinacolone) give very low yields of product. 

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