Dihydrocarvone-8,9-epoxide

The synthesis of l(7)-menthene-2,8-diols (655) has been mentioned (Vol. 4, p. 526, Ref. 503) the two isomers have now been isolated from Osmitopsis asteriscoidesThe known acetate 656, an insect repellent, has been isolated from Mentha haplocalyx oil, and a review of synthetic methods has been published by Verghese. In this connection, attention is drawn to a method for reducing an epoxide in the presence of a ketone, by reaction with phenyl telluride anion, PhTe, then triphenyltin hydride. The dihydrocarvone epoxides (657) yielded the hydroxy dihydroketone 658 corresponding to 656. Note also... 

Finally, we mention here recent progress made in the Bayer-Villiger oxidation. Zeolite Sn-Beta (1.6 wt.% Sn) was found to be an excellent catalyst [25], Thus, the monoterpene dihydrocarvone gives - with Sn-Beta and H202 - exclusively the lactone (Scheme 5.7), whereas m-chloroperbenzoic acid and Ti-Beta/H202 give the epoxide as the main product. 

Cavallo et al. from (+)-dihydrocarvone and evaluated in the asymmetric epoxida-tion of several silyl enol ethers [32]. Enantiomeric excess up to 74% was achieved in the epoxidation of the TBDMS trans-enol ether of desoxybenzoin with the fluoro ketone 19d (30 mol% of the ketone catalysts). In earlier work Solladie-Cavallo et al. had shown that the fluoro ketones 19a and 19e can be used to epoxidize trans-stilbene with up to 90% ee (30 mol% ketone catalyst) [33], Asymmetric epoxidation of trans-methyl 4-para-methoxycinnamate using ketone 19e as catalyst is discussed in Section 10.2. 

The authors used (5)-carvotanacetone (dihydrocarvone) as starting material (Scheme 34). To prepare the linearly conjugated sUylenol ether, they used the Kharash protocol and attained y-alkylation by Mukaiyama aldol reaction with trimethylorthoformate (195). The ketoacetal 295 was a-hydroxylated according to Rubottom by silylenol ether formation followed by epoxidation and silyl migration. Acid treatment transformed 296 to the epimeric cyclic acetals 297 and 298. endo-Aceta 297 was equilibrated thereby increasing the amount of exo-acetal 298. The necessary unsaturated side chain for the prospected radical cyclization was introduced by 1,4-addition of a (trimethylsilyl)butynylcopper compound. 

Other useful p-menthane syntheses of no great novelty are of cis- and trans-piperitol from 2a,3o -epoxycarane (silica-catalysed rearrangement to ds-p-menth-2-en-l,8-diol is also reported), of ( )-dihydrocarvone, isopulegone, and p-menthofuran via /S-keto-sulphoxides, of p-mentha-l,4(8)-diene via a bromination-dehydrobromination sequence, and of trans-carveol by benzoyl peroxide-CuCl oxidation of a-pinene. Further details for the conversion of (-)-(142) into (+)-(142), via its epoxide, are reported (Vol. 5, p. 25 cf. Vol. 3, p. 44). " ... 

Oxygenated p-Menthanes. The conformations of dihydrocarvone (148), the diastereoisomeric pairs of the corresponding 1-hydroxy-compound, and some related substances have been studied by temperature-dependent c.d. The conformations of the various stereoisomers (149) of the reduction products of carvotanacetone epoxide, as well as some of the corresponding alcohols from carvone epoxide (150) have been examined through their Hn.m.r. spectra. ... 

Scheme 9.9 The selective oxidation products of dihydrocarvone with H2O2 depend on the catalyst used Ti-P catalyses epoxidation, whereas Sn-P catalyses reaction to the lactone.

Dihydrocarvone can be epoxidized to give the corresponding epoxylactone (72). This compound can be used as a multifunctional monomer and as a crosslinking agent in ring opening metathesis polymerization. 

Carvone (93 ) was metabolized by actinomycetes to give -f-trans- (81a ) and -)-cis-car-veol (81b ) and (-t)-dihydrocarvone (101a ) as reduced metabolites. Compound 81b was further metabolized to (-t-)-bottrospicatol (92a ). Furthermore, 93 was hydroxylated at C-5 position and C-8, 9 position to give 5p-hydroxy-(-)-carvone (98a ) and (-)-carvone-8,9-epoxide (96 ), respectively. Compound 98a was further metabolized to Sp hydroxyneodihydrocarveol (lOOaa ) via Sp hydroxydihydrocarvone (99a ) (Noma, 1979a,b, 1980) (Figure 19.111). 

Limonene (68) was biotransformed via limonene-l,2-epoxide (69) to 8-p-menthene 1,2-frani -diol (71b). On the other hand, (-i-)-carvone (93) was biotransformed via (-)-isodihydrocarvone (101b) and la-hydroxydihydrocarvone (72) to (-i-)-8-p-menthene-l,2-tran5 -diol (71a) (Noma et al., 1985a, 1985b) (Figure 14.28). A soil Pseudomonad formed 1-hydroxydihydrocarvone (72), 8-p-menthene-l,2-tra i-diol (71b) from (-i-)-limonene (68). Dhavalikar and Bhattacharyya (1966) considered that the formation of 1-hydroxy-dihydrocarvone (66) is from dihydrocarvone (64). 

Group 1. Carvone (93)-dihydrocarvones (lOl)-dihydrocarveol (102)-dihydrocarveol-8,9-epoxide (103)-dihydrobottrospicatols (105)-5-hydroxydihydrocarveols (100)... 

In 2000, Solladie-Cavallo synthesized fluorinated ketones 408 from (+)-dihydrocarvone and investigated them in the asymmetric epoxidation of different fran -stilbenes and silyl enol ethers (Fig. 7.20) [285-287]. Later she reported rigid fran -decalones 409 which gave up to 70% ee (409a) and 20% ee (409b) in the epoxidation of ran -P-methylstyrene (Fig. 7.20) [288]. 

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