A range of amines was reacted with norcantharidin (2) to provide the corresponding norcantharimides (9–43). Treatment of norcantharidin with allylamine afforded the corresponding allyl-norcantharimide (20) which was amenable to epoxidation (mCPBA, 22) and subsequent ring opening (MeOH/H⁺; 23) or alternatively, osmylation (OsO₄/NMO; 24). These simple synthetic modifications of 2 facilitated the development of a novel series of norcantharimides displaying modest to good broad spectrum cytotoxicity against HT29 and SW480 (colorectal carcinoma); MCF-7 (breast adenocarcinoma); A2780 (ovarian carcinoma); H460 (lung carcinoma); A431 (epidermoid carcinoma); DU145 (prostate carcinoma); BE2-C (neuroblastoma); and SJ-G2 (glioblastoma). Analogues possessing a C₁₀, C₁₂ or C₁₄ alkyl chain or a C₁₂ linked bis-norcantharimide displayed the highest levels of cytotoxicity.
Bioorganic and Medicinal Chemistry Vol. 15, Issue 18, p. 6126-6134