Abstract: Methods, compositions, and devices for synthesis of therapeutically useful compounds. The invention provides a rapid approach for combinatorial synthesis and screening of libraries of derivatives of therapeutically important classes of compounds such as benzodiazepines, prostaglandins and .beta.-turn mimetics. In order to expediently synthesize a combinatorial library of derivatives based upon these core structures, general methodology for the solid phase synthesis of these derivatives is also provided. This disclosure thus also describes an important extension of solid phase synthesis methods to nonpolymeric organic compounds.