A novel synthesis of chimmitecan

10-Hydroxy-camptothecin (2) was treated with N-bromosuccinimide (NBS) in N,N-dimethylformamide (DMF) to give bromide 5. The protection of the hydroxy 1 groups of bromide 5 with ethyl chloroformate afforded 6, which was reacted with allyltri-n-butyltin via Stille coupling reaction to give the coupling product 7. Subsequently, compound 7 was hydrolyzed to give the target compound. Purification via column chromatography on silica gel gave chimmitecan with more than 99.8% purity and with single impurity less than 0.1%. Structures of all compounds were confirmed by ¹H NMR, ¹³C NMR, LRMS and HRMS techniques.