Biogenetically Atypical Aliphatic Acids and Esters

Bourgeanic acid (78) isolated from Ramalina bourgeana, R. evernioides ( = Niebla evernioides) (18) and Sterepcaulon tomentosum (32) can be considered an aliphatic depside and appears to be a biogenetic oddity since by inspection the component hydroxy acids would appear to arise from three propionate and one acetate units. However labelling experiments 

A structurally rather bizarre lipid is the monoacetylpentol (83) isolated from Alectoria ochroleuca (305). Besides spectroscopic evidence, periodate oxidation of (83) apparently produced a mixture of 8-acetoxyoctanal (84) and 2-ethyl-2-pentylpropan-1,3-dial (85) which were isolated as the corresponding 2,4-dinitrophenylhydrazones and characterised by mass spectroscopy (305). The polyester, methyl hexa(a-hydroxyvalerate) (86) has been isolated from Cetraria nivalis and Cladonia gonecha (35). 

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