Concise total syntheses of dl-camptothecin and related anticancer drugs

W Shen, CA Coburn, WG Bornmann…

Index: Shen, Wang; Coburn, Craig A.; Bornmann, William G.; Danishefsky, Samuel J. Journal of Organic Chemistry, 1993 , vol. 58, # 3 p. 611 - 617

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Citation Number: 109

Abstract

The readily available tricyclic ester 10 has been converted to dl-camptothecin (1) in 39% yield. It was discovered that, with the C5 carbomethoxy group in place, the c6 benzylic position of 10 (pyridone numbering) is selectively deprotonated by sodium hexamethyldisilazide. This allows for condensation with benzaldehyde to produce acid 17 which, after ozonolysis and methylation, afforded the tricyclic keto ester 16. The latter is ...