Lycopadiene

Derenne S., Largeau C., Casadevall E., and SeUier N. (1990) Direct relationship between the resistant biopolymer and the tetraterpenic hydrocarbon in the lycopadiene race of Botryococcus braunii. Phytochemistry 28, 2187—2192. 

Metzger P., Casadevall E. (1987) Lycopadiene, a tetrater-penoid hydrocarbon from new strains of the green alga Botryococcus brnunii. Tetr. Letts 28, 3931—4. 

Ozonolysis of lycopadiene followed by oxidative cleavage of the ozonide afforded 6,10,14-trimethylpentadecan-2-one thus establishing the C(14)-C(15) and C(18)-C(19) location of the unsaturations. Moreover, the optical rotation of this ketone was identical with that observed for the 6(R),10(R), 14-trimethylpentadecan-2-one obtained from ozonolysis of natural phytol this result allowed assignment of stereochemistry to the asymmetric centers. Therefore, lycopadiene (45) was identified as... 

On the basis of the configuration of the four chiral centers, a biosynthetic pathway can be proposed with phytol as precursor. In this mechanism, two phytyl chains would condense, probably as pyrophosphate derivatives, to produce the prelycopadiene pyrophosphate (46), which would be converted to lycopadiene (45) by addition of a hydride ion to a rearranged cyclopropylcation. An intermediate analogous to (46) is known to occur in the synthesis of phytoene, the precursor of the carotenoids in this latter case two geranylgeranyl pyrophosphates are condensed (45). In another possible pathway, lycopadiene (45) would merely result from reduction of phytoene. 

Metzger, P., and E. Casadevall Lycopadiene, a tetraterpenoid hydrocarbon from new strains of the green alga Botryococcus braunii. Tetrahedron Letters 28, 3931 (1987). 

Metzger, P., B. Allard, E. Casadevall, C. Berkaloff, and A. Coute Structure and chemistry of a new chemical race of Botryococcus braunii (Chlorophyceae) that produces lycopadiene, a tetraterpenoid hydrocarbon. J. Phycol. 26, 258 (1990). 

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