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Stereo and regioselectivity in ''Activated'' tritium reactions

Conference ·
OSTI ID:7095249
To investigate the stereo and positional selectivity of the microwave discharge activation (MDA) method, the tritium labeling of several amino acids was undertaken. The labeling of L-valine and the diastereomeric pair L-isoleucine and L-alloisoleucine showed less than statistical labeling at the ..cap alpha..-amino C-H position mostly with retention of configuration. Labeling predominated at the single ..beta.. C-H tertiary (methyne) position. The labeling of L-valine and L-proline with and without positive charge on the ..cap alpha..-amino group resulted in large increases in specific activity (greater than 10-fold) when positive charge was removed by labeling them as their sodium carboxylate salts. Tritium NMR of L-proline labeled both as its zwitterion and sodium salt showed also large differences in the tritium distribution within the molecule. The distribution preferences in each of the charge states are suggestive of labeling by an electrophilic like tritium species(s). 16 refs., 5 tabs.
Research Organization:
Brookhaven National Lab., Upton, NY (USA); Pennsylvania Univ., Philadelphia (USA). Cerebrovascular Research Center; Columbia Univ., New York (USA). Coll. of Physicians and Surgeons
DOE Contract Number:
AC02-76CH00016
OSTI ID:
7095249
Report Number(s):
BNL-41770; CONF-880787-2; ON: DE89001099
Country of Publication:
United States
Language:
English