Santalane and Bergamotane

A lettuce seed germination stimulant, graphinone, isolated from Graphium fungus culture has been attributed the structure (114). This compound appears to be identical to ovalicin, isolated from Pseudeurotium ovalis.  

A very short and efficient synthesis of j5-cuparenone (115) has been reported, in which ethyl p-tolylacetate was converted to the hydroxy-vinyl chloride (116) 

A third synthesis of thujopsene (120, R = Me) has been recorded, in which the diazoketone decomposition of (121) once again proved to be the crucial step in the synthetic route. Photosensitised oxygenation of thujopsene and thujopsenol 

Munakata, Agric. and Biol. Chem. (Japan), 1970,34, 649. 

Two almost simultaneous communications reported the successful syntheses of a-cedrene (123) and cedrol (124). Both syntheses were modelled along a proposed biogenetic scheme, and as such the penultimate goal was the generation of the cation (125) which should, and did, undergo a smooth acid-catalysed cyclisa-tion to a-cedrene. The two pathways to this cation differed in several respects yet practically coincided at the key spiro-dienone ester (126, R = Me and R = Et ). Whereas Crandall and Lawton completed the synthesis by formic acid treatment of the alcohol (127), Corey et al. found that similar treatment of the diol (128) also yielded a-cedrene, albeit in lower yield. Alternatively, the ene-diol (129) was converted into a-cedrene in better yield by formic acid treatment, thermolysis of the derived formates and subsequent lithium-ethylamine reduction of the diene (130). Finally, cedrol (124) was obtained by boron trifluoride cyclisation of the enol-acetate (131), followed by methyl-lithium treatment of the intermediate cedrone. 

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