Synthesis of D-glucose-1-C-14 and D-mannose-1-C-14

Abstract

Heretofore , radiochemical yields of sugars position-labeled with carbon-14 have been only 5 to 10 percent. Th is paper reports an improved cyanohydrin synthesis, and the preparation of D-glucose-l-CH and D-rnannose-I-C14 from D-arabinose in y ields of about 50 percent . L ow yields in prior syntheses appear t o have been due to several inefficient steps, and to t he fact that extension of the carbon chain yields a pair of epimeric sugar d erivat ives, t he proportion of which may not favor the desi red epimer. In t he classical cyanohydrin synthesis of glucose from D-arabinose only 30 percent of the product goes to t he gluconic epimer. To increase t he yield of glucose, a systematic study was made of thc proportions of the epimers formed from D-arabinose under a variety of conditions. It was found t hat the r atio of the epimers depends upon t he conditions under which the reaction of the sugar with cyanid e takes place. Thus, D-arabinose and cyanide, in the presence of sodium bicarbonate and carbon dioxide, yield about t hree parts of rnannonic nitr ile to one part of gluconic nitrile, bu t, in t he presen ce of sodium carbonate the proportion is approximately reversed .