Maintain and operate a specialized laboratory for the synthesis of selected anti-cancer and anti-AIDS compounds labeled with carbon-14, tritium or sulfur-35. Develop the radiosynthesis of such drugs selected by NCI. The label will be incorporated at a desirable site of the molecule by a carefully selected synthetic sequence or by a suitable exchange procedure. Efforts will concentrate on finding optimal conditions for such labeling in non-radioactive and/or tracer experiments. The optimum reaction conditions will then be applied to the synthesis of radioactive materials on preparative scale. Special attention will be paid to the achievement of high molar specific radioactivity and chemical and radiochemical purity (>98%). Maintain complete data sheets and records of detailed laboratory procedures or individual products. All compounds will be stored at conditions most suitable for each product, including storage in radiolysis preventing solvents and storage at -80 degrees in a freezer dedicated to this project. Specific amounts of radiolabeled compounds synthesized in this project, will be shipped by Federal Express to designated investigators. Packaging and shipping will comply with the regulations of US Department of Transportation.