158 



J. BADDILEY 



cautious acid hydrolysis to give 5'-deoxy-5'-methylthioinosine, identical 

 with "hypoxanthine thiomethyl pentoside." 



-0- 



MeCMe 

 /\ 







1 I 

 '-CH-CH-CH-CH-CH,-OTs 



N^^N 



OH 



KSMe 



OH ^^ 



MeCMe 



/\ 

 O 



CH • CH • CH • CH • CH, • SMe 



O 1 



OH OH I 

 I I I 

 L-CH-CH-CH CH-CH2-SMe 



N 



OH 

 Hypoxanthine thiomethyl pentoside 



■0- 



OH OH 



L-CH • CH • CH • CH • CH2 • SMe 



NH, 



Adenine thiomethyl pentoside 



This synthesis establishes the |8-configuration at the glycosidic center. 

 Adenine thiomethyl pentoside itself is synthesized in poor yield by a similar 

 series of reactions upon 2',3'-isopropylidene-5'-p-toluenesulfonyladeno- 



104-106 



sme/ 



It is now known^"^ that adenine thiomethyl pentoside arises in Nature 

 by decomposition of the transmethylation intermediate "active meth- 

 ionine." This intermediate has the structure^ "^^ ^^^ shown as XVIII. 



-0- 



OH OH 



Me 



NHj 



I 



•-CH-CH-CH-CH-CHj-S-CHs-CHj-CH-COr 



NHa 



XVIII 

 "Active methionme' 



h. Crotonoside (9-j3-D-ribofuranosylisoguanine) 



This was first isolated from the bean Croton tiglium. It is isomeric with 

 guanosine and gives on acid hydrolysis D-ribose and isoguanine.^"^ Its ab- 



106 F. Weygand and O. Trauth, Ber. 84, 633 (1951). 



»" J. Baddiley, G. L. Cantoni, and G. A. Jamieson, /. Chem. Soc, 1953, 2662. 



'08 G. L. Cantoni, /. Am. Chem. Soc. 74, 2942 (1952). 



109 E. Cherbuliez and K. Bernhard, Helv. Chim. Acta 15, 464 (1932). 



