Cyclocolorenone sesquiterpenes

In acetic acid the intermediate zwitterion is trapped by acetate affording cyclopentenones with an acylated hydroxymethylene group on C-4. Use of this sequence has been made of in the synthesis of the sesquiterpenes cyclocolorenone 347) (3.31) and a-cadinol (3.32) 348). 

In Frullania, twenty-five taxa have been investigated chemically (27,34). Fourteen species contained allergy-inducing sesquiterpene lactones such as (322, 338, 339, 345, 349). Eighteen species bibenzyl derivatives (595—598, 600—608). The major constituents are sesquiterpene lactones and bibenzyls, which may be valuable chemosystematic markers of Frullania species. Frullania species are divided into five chemotypes, a sesquiterpene lactone-bibenzyl type (Type I), a sesquiterpene lactone-type (Type II), a bibenzyl-type (Type III), a monoterpene-type (Type IV) and a cyclocolorenone (38)-type (Type V). Except for the cyclocolenone-type, there is no chemical affinity between the Frullaniaceae and the Porellaceae. 

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