P-Menthane-l,8-diol

Terpin n. Terpinol, 4-hydroxy-a,a,4-tri-methylcyclohexanemethanol. Additional names p-menthane-l,8-diol dipentenegly-col. Molecular formula C10H20O2. Molecular weight 172.26. Percent composition C 69.72%, H 11.70%, O 18.58%. Literature references from Merck Index, 13th edn. 2001 Both cis-and trans-modifications are known. The ds-compound is obtained most readily in the hydrated form, cis-terpin hydrate. Prepn of ds-form from oil of turpentine Hempel, Ann. 180, 71 (1876) Wallach, Ann. 230, 225 (1885) Schmitt, Mfg. Chemist 26, 350 (1955). From d-limonene Sword, /. Chem. Soc. 127y 1632 (1925). Prepn of trans-form from 1,8-cineole, oc-terpineol or ds-terpin hydrate. Matsuura et al. (1958) Bull Chem Soc Japan 31, 990. Lombard, Ambroise, Bull... 

In 1907 Wallach [65] identified 1,4-cineole (or cineole l-isopropyl-4-methyl-7-oxabicyclo[2.2.1]heptane, 13) that forms by acid-promoted dehydratation of 1,8-terpin (p-menthan-l,8-diol) [66]. A two-step protocol preparation of 13 from a-terpineol (p-menth-l-en-8-ol) has been presented [67] cineole is present in many... 

Based on the aforementioned results, it is obvious that (+)-3p-hydroxy-l,8-cineole (123b) is formed mainly in the biotransformation of 1,8-cineole (122), (+)-3a-hydroxy-l,8-cineole (123b), and (+)-3-oxo-l,8-cineole (126a) by S. ikutamanensis Ya 2 1. The production of (+)-3p hydroxy-l,8-cineole (123b) is interesting, because it is a precursor of mosquito repellent, p-menthane-3,8-diol (142aa ) (Noma and Nishimura, 1981) (Figure 19.136). 

The use of topical repellents applied to exposed skin is the most important personal intervention against vectors of diseases, and numerous studies have been undertaken to enumerate the protection against biting vectors, especially mosquitoes. The use of repellent active ingredients such as A,A-diethyl-3-methylbenzamide (deet), 2-(2-hydroxyethyl)-l-piperidinecarboxylic acid 1-methylpropyl ester (icaridin, picaridin), lemon eucalyptus oil (p-menthane-3,8-diol) and ethyl butylacetylaminopropionate (IR3535), as well as several infrequently used synthetic and naturally derived active ingredients are discussed in detail in Chapter 19. 

Scheme 9 Stereoselective synthesis of cw-p-menthane-l,7,8-triol (A) and cA-p-menth-8-ene-l,7-diol (B).

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). " ... 

Meliatoxin Aj, in T-10108 Meliavolen, M-30029 Meliracemoic acid, M-10029 Melissic acid, see T-lOlOO Melithasterol B, in E-30063 Melitric acid A, M-20031 Melitric acid B, M-20032 Melomorsine, M-20033 Meloscandonine, M-20034 Membrenone A, M-30030 Membrenone B, M-30031 Membrenone C, M-30032 Menisidine, in F-lOOOl Menispermacide, M-20035 Menoxymycin B, M-30033 / -Menthane-3,8-diol, M-30034 p-Menthane-l,7,8-triol, M-20036 / -Menthane-l,8,9-triol, M-20037 /7-Mentha-1,3,5,8-tetraene-2,5,9,10-tetrol, M-30035... 

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