Chlorinated monoterpenes

Ali, M.S. et al., A chlorinated monoterpene ketone, acylated (J-sitosterol glycosides and a flavanone glycoside from Mentha longifolia (Lamiaceae), Phytochemistry, 59, 889, 2002. 

Ali MS, Saleem M, Ahmad W, Parvez M, Yamdagni R (2002) A Chlorinated Monoterpene Ketone, Acylated (3-Sitosterol Glycosides and a Flavanone Glycoside from Mentha longifolia (Famiaceae). Phytochemistry 59 889... 

Stuthridge, T. R., A. L. Wilkins, A. G. Longdon, K. L. Mackie, and P. N. Mac-farlane. 1990. Identification of novel chlorinated monoterpenes formed during kraft pulp bleaching of Pinus radiata. Environ. Sci. Technol. 24 903-908. 

A synthesis of the monoterpene alkaloid ( )-actinidine has been accomplished through the intramolecular cycloaddition of a substituted pyrimidine (81JCS(P1)1909). Condensation of the diester (756) with formamidine provided the pyrimidine precursor (757) which when heated at its melting point (203 °C) underwent cycloaddition with elimination of isocyanic acid to produce the pyridone (758). Conversion of the pyridone into the chloropyridine was effected with phosphoryl chloride. The chlorine atom was then removed by hydrogenoly-sis over palladium on charcoal to afford the racemic alkaloid (759 Scheme 175). 

The pyran metabolites, pantopyranoids A-C (231-233), have been isolated from the Antarctic alga Pantoneura plocamioides (494). This seaweed and Plocamium cartilagineum contain plocamiopyranoid (234) and 235, and pantoneurines A (236) and B (237) (496). The Pakistani herb Mentha longifolia has yielded the novel chlorinated menthone longifone 238 (497), one of the few known terrestrial halogenated monoterpenes. 

There are several cyclic ethers derived from acyclic monoterpenes which are of importance at lower levels in fragrances. Allylic oxidation of citronellol can be used to introduce a leaving group which allows cyclization to form the pyran, rose oxide. Chlorination was one of the first oxidation techniques employed various others, including electrochemical methods, have since been developed. An outline of the synthesis is given in Scheme 4.16. Rose oxide occurs in rose and geranium oils, to which it imparts a characteristic dry, green, rosy top-note. 

Technical toxaphene is a mixture of polychlorinated monoterpenes obtained by chlorination of camphene under UV irradiation. Introduced in 1945, toxaphene was mass-produced until the mid-1980s and widely used as an insecticide, especially in cotton cultures. Currently, toxaphene is considered a worldwide... 

C oH 5, Mr 136.24, crystalline, bicyclic monoterpene with isocamphane structure occurring in nature in two optically active forms and a racemate (l/f,45)(+)- and (15,4/f)(-)-C., mp. 50-51 °C, [a]j, 119° (benzene) ( )-C., mp. 47 °C. Optically active C. racemizes readily. thus various values for optical rotation are found in the literature. C. occurs in many essential oils, e.g., Ceylon, citronella, turpentine, and bergamot oil. Use In the perfume industry and for production of camphechlor (toxaphen), a chlorinated C. that was used as an insecticide. Since it accumulates in the body fat of mammals its use as crop protection agent is no longer permitted in Germany. 

Reactions of (dichloroiodo)benzene with various monoterpenes in methanol proceed via the ionic mechanism and afford the respective products of chloromethoxylation of the double bond with high regio- and stereoselectivity [56]. Likewise, the reaction of a recyclable chlorinating reagent, 4,4 -bis(dichloroiodo)biphenyl... 

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