SYNTHESIS OF [1-C-11]D-GLUCOSAMINE AND EVALUATION OF ITS INVIVO DISTRIBUTION IN RAT WITH PET

D-Glucosamine is a structural unit of many biologically interesting ma cromolecules. To investigate the feasibility of using labelled D-gluco samine as a tracer for anabolic processes, a two-step synthetic proced ure for specifically labelling D-glucosamine in position 1 with carbon -11 was developed. [C-11]Cyanide was reacted with an imine precursor, N-benzyl-D-arabinosylamine, to generate the [1-C-11]alpha-amino nitril e. Reduction to [1-C-11]D-glucosamine was accomplished by catalytic hy drogenation using PdCl2 and the N-benzyl group was simultaneously remo ved. The total synthesis time from end-of-trapping of [C-11]cyanide wa s 40-45 min and the decay-corrected radiochemical yield was 5-10% afte r HPLC isolation. The biodistribution of [1-C-11]D-glucosamine in rat following i.v. bolus injection was investigated using positron emissio n tomography and showed that the availability of this substance for CN S anabolism is low with the primary limitation being the intact blood- brain barrier.