 He was particularly noted for the total synthesis of heterocyclic drugs and natural products, including porphyrins, camptothecin, saxitoxin, psoralens, antibiotics, antitumor compounds, and opium alkaloids such as morphine, codeine, and hydromorphone.His research led to the publication over 400 papers and 33 patents.His discoveries were the scientific foundation for numerous companies that Rapoport helped to start including HRI Research, HRI Associates, Advanced Genetics Research Institute, Cerus Corporation, ChemQuip, and Oncologic.