SYNTHESIS 



S. cerevisiae. On treatment with Raney nickel, it was converted into 



the biologically active f^/-desthiobiotin. 



Some of these methods have been patented by Lederle Labs. Inc.^^" 

 An entirely different type of synthesis from those already described 



was patented by Roche Products Ltd.^^ -pj^g most striking feature of 



this method is that the imidazolidine ring is built up before the thio- 



phane ring : 



CH . COOH CHBr . COOH Bz . NH . CH . COOH coci, 



HOOC . CH CHBr . COOH Bz . NH . CH . COOH 



CO CO CO 



/\ ^\ /\ 



Bz . N N . Bz AcoO Bz . N N . Bz H, Bz . N N . Bz 



11 — 11 ^ II 



CH CH CH CH CH CH 



II II II 



COOH COOH CO CO AcO . CH CO 



O o 



CO CO 



/\ / \ 



Bz . N N . Bz Bz . N N . Bz 



II II 

 ^ CH CH > CH CH > 



I I I .OH 



CO CHa C< 



s s 



CO CO 



^(CH2)40CH 



Bz . N N . Bz Bz . N N . Bz 



II H3 I I 



CH CH »• CH CH 



II II 



CH2 C=CH . (CH2)30CH3 CHj CH . (CH^), . OCH, 



Na + 



CO 



'\ 



NH N . Bz 



I I 



CH CH 



I I 



CH2 CH. (CHa)^. OCH3 



The 8-methoxy group was converted into the carboxy group via 

 the bromide and cyanide, and, finally, the protective benzoyl group 

 was removed by means of sodium and ammonia. 



419 



