BIOTIN 



yeast to convert desthiobiotin into biotin, since the former disappeared 

 from the incubated culture and was replaced by a substance with 

 growth-promoting properties for L. helveticus.^* ^^ 



Desthiobiotin was synthesised in several ways. J. L. Wood and 

 V. du Vigneaud ^' used the following method : 



CH.lCOOC^Hs)^ + Br(CH,)5.COOC,H6 > {C,ll,OOC), .CH. {C¥L,),.COOC;tl, 



HOOC . CH . (CH^)^ . COOH ^,^0 CH3 . CO . CH . {C-ii,)s . COOH 



' NH . CO . CH, 



1. Saponification 



2. Bromination 



3. Amination 



4. Decarboxylation 



NH5 



HCl 



KONG 



CH. 



CO 

 NH NH 

 C=C . (CHa)^ . COOH 



CH3 . CO . CH . (CH2)5 . COOH 

 NH2 

 CO 

 NH NH 

 CH3 . CH— CH . (CHa)^ . COOH 



Melville ^^ prepared it by the action of phosgene in alkaline solu- 

 tion on its degradation product, ^77-diaminopelargonic acid, whilst R. 

 Duschinsky and L. A. Dolan ^^ synthesised it by the following route : 



HNO2 _^ ^ ^^^^ TT 



I 01 . CO . (CH2)4 . COOC2H5 



CO 



/\ 



NH NH 

 CH3 . C=C . CO . (CH2)4 . COOC2H5 



H2O 



CO 



/ \ 



NH NH 

 CH3 . CH CH . {CU,), . COOH 



448 



