Terpenes menthane derivatives 328

Rule 5 Form the above types of names for all hydrocarbon terpene radicals derived from menthane-type monocyclic hydrocarbons regardless of the position of the point or points of attachment that is, the H or H s may be removed from carbons in the ring or from carbons in the numbered side chains. Use position numbers to designate the position of the point or points of attachment in the radicals. 

Monocyclic terpenes are derived, for the most part, from the cis-trans-isomcrs of -menthane. Trans-p-mcrdhans itself occurs in the oil of turpentine. Its o- and m-isomers are rarely occurring rearrangement products of -menthane. 

For the Type A monocyclic terpene hydrocarbons (para, ortho, and meta derivatives of menthane) use the menthane, menthene, and menthadiene names and the well-established fixed numbering of menthane. 

Several teachers expressed the opinion that they would like to see the numbering assigned to menthane (whether it is the historical numbering or a new numbering) retained for bicyclics and other terpene derivatives to simplify the following through a series of terpene transformation reactions. 

For the parent compound of the menthane-type (Type A) monocyclic terpene hydrocarbons, the name menthane, its well-established fixed numbering of the carbon skeleton, and extension of nomenclature rules to apply to double bonds outside the ring have been recommended (for the p-form, see Formula 6, Chart 5, p. 19). These recommendations and the extension of nomenclature practices to apply to points of attachment outside the ring are basic to the rules for forming the names of menthane-type monocyclic radicals. Since the enumeration of the parent compound is fixed, the position number of a point of attachment in radicals derived from it is predetermined and will not always be numbered as 1. 

Rule 1 Form the names of univalent radicals derived from menthane (the saturated parent hydrocarbon of menthane-type monocyclic terpenes) by replacing the ane ending of the hydrocarbon name with "y/ . That is menthyl. 

Rule 2 Form the names of univalent radicals derived from the unsaturated menthane-type monocyclic terpene hydrocarbons containing one double bond, which may be either in the ring or outside the ring, by replacing the final e" of the hydrocarbon name (menthene) with "yV That is menthenyl. 

The menthane-type radicals given below are based on the p-form of menthane. Names of the radicals derived from the few known o- and m-menthane-type mono-eye lies would be analogous. The established fixed numbering for p-menthane is shown on the formula for p-menthyl the position numbers in all of the recommended radical names are based on this numbering. The names in parentheses shown below some of the recommended names are the common terpene radical names. Examples ... 

Planar chiral compounds should also be accessible from the chiral pool. An example (with limited stereoselectivity) of such an approach is the formation of a ferrocene derivative from a -pinene-derived cyclopentadiene (see Sect. 4.3.1.3 [81]). A Cj-symmetric binuclear compound (although not strictly from the chiral pool, but obtained by resolution) has also been mentioned [86]. Another possibility should be to use the central chiral tertiary amines derived from menthone or pinene (see Sect. 4.3.1.3 [75, 76]) as starting materials for the lithiation reaction. In these compounds, the methyl group at the chiral carbon of iV,iV-dimethyl-l-ferrocenyl-ethylamine is replaced by bulky terpene moieties, e.g., the menthane system (Fig. 4-2 le). It was expected that the increase in steric bulk would also increase the enantioselectivity over the 96 4 ratio, as indicated by the results with the isopropyl substituent [118]. However, the opposite was observed almost all selectivity was lost, and lithiation also occurred in the position 3 and in the other ring [134]. Obviously, there exists a limit in bulkiness, where blocking of the 2-position prevents the chelate stabilization of the lithium by the lone pair of the nitrogen. 

From Menthane.— Taking up these compounds in the same order in which we considered the terpenes themselves we have first the alcohols and ketones derived from menthane, the saturated mono-cyclic terpene. The more common alcohol is known as menthol, menthanol or terpanol and the corresponding ketone is named similarly menthone, menthanone or terpanone. Both of these compounds are present in Japanese, Russian and American peppermint oil the former occurring both as the free alcohol and as the acetic acid ester. Menthol is a crystalline solid, m.p. 42°, b.p. 213°. It has the characteristic peppermint odor and is used as a disinfectant and as a mild anesthetic for headache. Menthone is a liquid, b.p. 207°. The constitution of both compounds is proven by their relationship to thjrmol, i-methyl 3-... 

Terpin. Terpin Hydrate. Cineol.—In addition to these monohydroxy derivatives there is another important one which is a dihydroxy menthane known as terpan-di-ol or terpin. Terpin boils at 258° and readily forms a crystalline hydrate, terpin hydrate, which melts at 117°. It also loses water yielding an anhydride known as cineol. Terpin and terpin hydrate are obtained from the terpenes in oil of turpentine by the action of acids. Cineol is found in eucalyptus oil. The constitution of these compounds is proven by their relation to geraniol (p. 167). When treated with 5 per cent H2SO4 two molecules of water are added to geraniol and terpin hydrate is formed. This by loss of one molecule of water forms a closed ring yielding terpin and this by loss of another molecule of water yields cineol. These relationships are as follows ... 

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