Allylic alcohols ozonolysis, ozone

Unexpected products sometimes arise on ozonolysis of alkenes bearing allylic heteroatoms. Draw the structure of the ozonide from the reaction of the allylic alcohol 13 with ozone and suggest an explanation for the formation of the product 14, used in a synthesis of grandisol. 

The structure of the ozonide from the reaction of the allylic alcohol 13 with ozone is shown below. This is the normal product from ozonolysis. Notice that there is no oxidant (such as H2O2) or reductant (such as Mc2S) in the formation of the keto-acid 14. The formation of the product 14 can be explained by fragmentation of the ozonide (see below), which occurs in a similar way to that described for the ozonolysis of a,p-unsaturated carbonyl compounds given in Scheme 5.105. See R. L. Cargill and B. W. Wright, / Org. Chem., 40 (1975), 120. 

When simple aldehydes were converted to allylic alcohols, they could be transformed to the corresponding trichloroacetimidates and subjected to thermal rearrangement to provide aUyl amines. The aUyl amine functionality was also accessible from enantio-selective reduction of propargyl ketones followed by conversion to the phthalamide derivative and reduction of the triple bond. Ozonolysis of these substrates provided the corresponding a-amino methyl esters in good yield (eq 48). As with the allyl alcohols, optically active substrates were treated with ozone without loss of enantiopurity of the chiral center. 

Deninno, M. P. "Anomalous ozonolysis of cyclic allylic alcohols Mechanism and synthetic utility. Journal of the American Chemical Society 1995,117(39), 9927-9928. Razumovskii, S. D. Rakovski, S. K. Zaikov, G. E. Influence of the Paraffine Hydrocarbon Structure on its Reaction Rate with Ozone. Izv. Akad. Nauk, ser. khim. 1975, 9,... 

The second synthetic approach to oidiolactone C (61) is summarized in Scheme 20. This route also commences with the ozonolysis of trans-communic acid 180. Now, when this compound was exposed to ozone in excess, keto aldehyde 187 was obtained in 76% yield. The key step in this approach was the y-lactone closure via chemoselective reduction of the lactone moiety on compound 189 through a SN2 mechanism. Compound 189 could be prepared by saponification of the corresponding methyl ester with sodium propanethiolate. Once the primary alcohol is oxidized, the completion of the synthesis of key lactone 103 only requires the allylic oxidation of the C-17 methyl with concomitant closure of the 8-lactone. This conversion was achieved with Se02 in refluxing acetic acid to give 103 in 51% yield. 

Ozonolysis of unsaturated hydroperoxy acetal 226, readily obtained by trapping carbonyl oxides with primary unsaturated allylic or homoallylic alcohols <1997J(P1)5>, with ozone in methanol/ether at —78°G gave the 6-hydroxy-l,2,4-trioxane derivatives 227 almost quantitatively and as a single isomer (structure confirmed by 1-D NOE spectroscopy see Scheme 64) <1997JOC4949>. In the case of substitution (R R = H, Me or Me, Me), a mixture of two and three isomers, respectively, were obtained, all completely assigned by H NMR spectroscopy <1997JOC4949>. 

---