550 



BIOTIN 



CHj-COCHj-COOCzHs "NO^ CHs-COCCOOCaHs 



VII II 



NOH 



CH3COCHCOOC2H5 



VIII I 



NH2 



HCNO 

 CO 



NH NH 



II II 



CH3C===CH CH3C C-COOCzHa 



IV J,C1C0(CH2)4C00C!H6 IX 



CO CO 



H2 



NH NH 



I I 



CH3-C CCO-(CH2)4COOC2H5 



V 



H2O 



-^ NH NH 



I I 



CH CH(CH2)5COOH 



VI 



Another method was used by Wood and du Vigneaud,^^ and again 

 another, although similar, by Bourquin et al.^'' In the latter synthesis the 

 following reactions were employed (X-XVI). 



CH3-CO-CHNa-COOC2H6 + Br- (CH2)5-COOC2H5 -^ 



X 



CH3-CO-CH-(CH2)5-COOC2H6 _koh^ CHa-CO-CH- (CH2)5-C00H CeH^Ni^Ci 



I 

 COOC2HB 



XI XII 



CH3-CO-C-(CH2)6-COOH -Sl^ CH3-C0-CH- (CH2)5-COOH J^CNO^ 



N-NH-CbHb 

 XIII 



CO 



/ \ 



N NH 



NH2 

 XIV 



CO 



/ \ 



NH NH 



H2 



CHj-C CH.(CH2)5-COOH — -^ CH3C CH- (CIl2)r.-C00H 



XV XVI 



«6 J. L. Wood and V. du Vigneaud, J. Am. Chem. Soc. 67, 210 (1945). 



0' J. P. Bourquin, O. Schnider, and A. Griissner, Hclv. Chim. Ada 28, 528 (1945). 



