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Treatment of the phaeofarnesins (4) isolated from the Chlorobium chlorophylls-660 (ex. Chloropseudomonas ethylicum) with sulphuric acid in methanol gives the methyl phaeophorbides (1) which can be dehydrated by refluxing in benzene in the presence of acid to afford the 2-vinyl derivatives (2) ; prolonged refluxing gives the novel cyclised compounds (6). By-products from handling the pigments are the 8'-acetylbilitrienes (5). obtained by photo-oxygenation. [l4CH3]-, [l3CCH,J -, and [ 13C2H,] -L-methionine are efficiently incorporated into the Chlorobium chlorophylls-660, showing that the extra methylation present in the &methyl, 4-isobutyl, 4-n-propyl, t The numbers 660 and 650 refer t o the wavelength (in nm) of the maximum in the red region of the electronic absorption spectra of the pigments in ether solution.

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