中文摘要：

目的 改进喜树碱关键中间体5′-RS-，5-二氧代-（5′-乙基-5′-羟基-2′H，5′H，6′H-6-氧代吡喃）-[3′，4′，f]-△^6（8）-四氢中氮茚（1）的合成工艺。方法 以6-氰基-1，1-亚乙二氧基-7-（1′-乙氧羰基）丙基-5-氧代-△^6（8）-四氢中氮茚（2）为原料，经氢化和亚硝化、脱氮、混合金属催化氧化、环合及三氟乙酸脱保护反应得到目标产物。结果与结论 新工艺简化了操作、缩短了反应时间，总产率达到了72．4％。

英文摘要：

Aim To improve the synthetic process of 5 ′-RS-1, 5-dioxo-（5 ′-ethyl-5′-hydroxy-2′H, 5′H, 6′H-6oxopyrano）-[3′, 4′, f ]- A^6（8）-tetrahydroindolizine, a key intermediate for the total synthesis of camptothecin. Methods The product was synthesized from 6-cyano-1, 1- （ethylenedioxy）-7- [ 1 ′- （ethoxycarbonyl）-propyl]-5-oxo-Δ^6（8）- tetrahydroindolizine by combined hydrogenation and nitrosation, elimination, mixed metal oxidation, cyclization and deprotection. Result and conclusion The intermediate is obtained in an overall yield of 72.4% according to new process, and the operation is simplified.