Novel synthesis and use of beta-lapachone analogs

3-Substituted- beta -lapachone analogs and their use either alone or to augment chemotherapy or radiotherapy to induce programmed neoplastic cell death without exhibiting toxicity to surrounding normal cells are disclosed. In particular, 3-allyl- beta -lapachones, 3-alkyl- beta -lapachones and 3-halo- beta -lapachones were found to be Topoisomerase (Topo I) inhibitors. When these analogs are used alone there is a reversible single-strand break in the DNA of neoplastic cells causing apoptosis and cell death in some cells. However, when these analogs are combined with chemotherapy or X-irradiation, an irreversible Topo I-mediated break is achieved. A new and more efficient chemical synthesis of the compounds is also disclosed.