Glycosides and Isoprenylated Carotenoids

Several bacterial species produce C45 and C50 carotenoids which contain one or two extra isoprenyl groups. Although their biosynthesis has not been studied, it is probable that instead of proton-initiated cyclisation at the polyene termini, attack by dimethyl allyl pyrophosphate results in substances such as the symmetrical decaprenoxanthin (P439) (68). The stereochemistry of the isolated acyclic double bond was shown to be trans by the n.m.r. spectrum of the corresponding aldehyde. Other carotenoids present in Flavobacterium 

Nitsche, K. Egger, and A. G. Dabbagh, Tetrahedron Letters, 1969,2999 H. Nitsche, Tetrahedron Letters, 1970, 3343. 

Francis, S. Hertzberg, K. Andersen, and S. Liaaen-Jensen, Phytochem., 1970, 9, 629. 

Francis, and S. Liaaen-Jensen, Acta Chem. Scand., 1969, 23, 2605. S. Liaaen-Jensen, S. Hertzberg, O. B. Weeks, and U. Schwieter, Acta Chem. Scand., 1968, 22, 1171. 

Schwieter and S. Liaaen-Jensen, Acta Chem. Scand., 1969, 23, 1057. 

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