Synthesis of <sup>3</sup>
H, <sup>13</sup>
C<sub>2</sub>
, <sup>2</sup>
H<sub>4</sub>
<sup>14</sup>
C-SCH 430765 and <sup>35</sup>
S-SCH 500946, potent and selective inhibitors of the NPY<sub>5</sub>
receptor
SCH 430765 and SCH 500496 are potent and selective antagonists of the NPY5 receptor. NPY5 receptorantagonists have the potential for the treatment of obesity. [35 S]SCH 500946 was prepared for a competition binding assay which led to the identification of SCH 430765. Three distinct isotopically labelled forms of SCH 430765 were synthesized. [3 H]SCH 430765 was prepared for a preliminary absorption