316 



Essays in Biochemistry 



OAc 



XXXlVb 



OAc 



7J O O 

 HC0 C^O^^ X C^CH 3 ) 2 



XXXIV a 



> 1 tert. OH 



XXXV Germine 



(9-fluorenones) on oxidation is quite in line with the assigned struc- 

 tures. 20 The contraction of ring A in XXIII may have its cause in 

 the multiple substitution of this ring, in cevine, with oxygen (cf. below) . 

 On the other hand, this explanation is not applicable to some of the 

 dehydrogenation products of jervine which likewise show this feature. 

 With the skeletal structure of cevine thus in essence defined by 

 XXIV, there remained still the formidable task of determining the 

 location of its eight oxygen atoms, all but one of which could be 

 assumed to be hydroxylic. Studies towards this end had been in prog- 

 ress since about 1951 in several laboratories, including those of Barton 

 (London), Jeger and Prelog (Zurich), and Woodward (Harvard). 

 Before long these investigators, by pooling their information, were able 

 to advance in a joint communication 1 structure XXV for cevine. It 

 is not possible to do justice here to the intricate and ingenious argument 

 essential to the elaboration of this formula, nor to survey the host of 

 experimental facts, some already on record from the work of Jacobs, 

 and many others of more recent vintage, which could be marshalled 



