Furanoid sesquiterpene

Such a secondary photoreaction can be avoided by trapping the unsaturated aldehyde, e.g. as a hemiacetal. This principle is demonstrated in the synthesis of a furanoid sesquiterpene (2.6)210). 

Davana oil is obtained by steam distillation of the herb Artemisia pallens Wall. (Asteraceae), grown in south India. It is an orange-brown liquid with a sweet tealike odor reminiscent of dried fruits. The composition of the oil is very complex its main components are furanoid sesquiterpenes [474-476a]. It is used predominantly for aroma compositions. FCT 1976 (14) p.737 [8016-03-3], [91844-86-9]. 

Gutzwiller and co-workers [84] have purified and checked two furanoid sesquiterpene alcohols by chromatography also on silica gel layers, using mixtures of chloroform and methanol. 

Schulte, G., P.J. Scheuer, and O.J. McConnell 221. Two Furanosesquiterpene Marine Metabolites with Antifeedant Properties. Helv. Chim. Acta 63, 2159 (1980). Guella, G., a. Guerriero, P. Traldi, and F. Pietra Penlanfuran, a New Furanoid Sesquiterpene from the Marine Sponge Dysidea fragilis (Mont.) of Brittany. A Striking Difference with the Same Hawaiian Species. Tetrahedron Lett. 24, 3897 (1983). 

Guella, G., Guerriero, A., Traldi, P., and Pietra, F. (1983) Penlafuran a new furanoid sesquiterpene from the marine sponge Dysidea fragUis (mont.) of Brittany. A striking difference with the same Hawaiian species. Tetrahedron Lett., 24, 3897-3898. 

In addition to being a rich source of furanoid sesquiterpenes, the sponge Disideapallescens has also yielded 191) a chromansesquiterpenoid, /-chromazonarol (237), which is the antipodal cyclic isomer of the algal hydroquinone zonarol (114). The biosynthesis of antipodal terpenoids by different organisms is of considerable interest. 

Lactaranolide derivatives included in Part 12 are produced by silica gel degradation of velutinal esters (7.28, 7.30), methylvelutinal (7.17) or free velutinal itself (for a discussion of these transformations see the chapter on chemical interconversions of Lactarius sesquiterpenes). The compounds upon acidification underwent aromatization to form furanoid derivatives (see Part 18). Under these conditions dehydration reactions took place and also dienes were formed (72). 

Several sesquiterpenes play well-defined and essential roles in higher and lower plants, including the hormone abscisic acid, furanoid phytoalexins, lactone antifeedants, and numerous fungal antibiotics (Herout, 1971 Rucker, 1972). No specific function has been demonstrated for most sesquiterpenes however, an allelopathic or allelochemic role is commonly ascribed to these compounds, as for monoterpenes. Like monoterpenes, sesquiterpenes are not metabolically inert, but are rapidly synthesized and catabolized (Croteau and Loomis, 1972 Francis, 1972) and thus may also play a dynamic role in metabolism. Virtually nothing is known about the catabolism of sesquiterpenes. 

Tam and Fraser-Reid have also prepared the geometric isomers of compound (7) as analogues of the furenone moieties found in many germacranolide sesquiterpenes (see outline in Scheme I), and compound (8) is a further branched-chain furanoid product obtained from a carbohydrate (Scheme 3). It is a synthon for the macrolide natural product maytansine. ... 

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