Guaiazulene sesquiterpenes

The main constituents of the oil are the sesquiterpene alcohols guaiol [489-86-1] and bulnesol [22451-73-6] [542]. The oil may be used as a starting material for the synthesis of guaiazulene, which has anti-inflammatory properties. 

Guella G, Skropeta D, Mancini I, Petra F (2003) Calenzanane Sesquiterpenes from the Red Seaweed Laurencia microcladia from the Bay of Calenzana, Elba Island Acid-Catalyzed Stereospecific Conversion of Calenzanol into Indene- and Guaiazulene-Type Sesquiterpenes. Chem Eur J 9 5770... 

The position of these substances in the chromatogram is determined by the polarity of the parent compound. Menthofuran migrates just behind guaiazulene [182 a, 247]. The terpene and sesquiterpene epoxides follow, lying in the upper part of the ester zone on silica gel G layers (Table 23) (cf. also [155]). in agreement with El-Deeb [55]. The carbonyl and alcohol oxides follow with lower hRf-values. This sequence holds even at — 9° C using Freon (Frigen 21) as solvent [255]. 

Anthozoa Recently, 15 new guaiazulene type sesquiterpenes have been described in a Chinese gorgonian Anthogorgia species [22]. 

In addition to common six-membered rings such as in the cadinenes, one classic bicyclic sesquiterpene is caryophyllene, which has a nine-membered ring and cyclobutane ring. Additional unsaturation provides aromatic bicyclic sesquiterpenoids such as vetivazulene and guaiazulene. Examples are caryophyllene, y-muurolene, petasin, Ipomeamarone, carotol, helminthosporal, avocettin, alkaloids of Nuphar, and mycophenolic acid. 

Guaiazulene is a bicyclic sesquiterpene obtained from guaiac wood oil, Callis intratropica Blue, and Matricaria chamomilla [73]. Guaiazulene showed cytotoxicity against cancer and normal cells by inducing an intrinsic apoptotic pathway and caspase-3 activation [74]. 

A multistep sequence to guaiazulene may cover a hydroformylation step [150]. The sesquiterpene, which is found in nature in the guaiac and chamomile oil, is used as an anti-inflammatory compound in cosmetics. The starting point for the synthesis considered here was dehydrolinalool, which was converted into a cyclopentene-based unsaturated ketone (Scheme 6.53). The hydroformylation took place exclusively on the exocyclic double bound. Subsequent steps afforded guaiazulene. 

Bay of Calenzana, Elba Island Acid-catalyzed stereospedfic conversion of calenzanol into indene- and guaiazulene-type sesquiterpenes. Chem. Eur. J 9, 5770-5777. 

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