Partial Synthesis of Vindorosine and Vindoline

In view of the importance of vindoline (44) as a constituent of the oncolytic bisindole alkaloid vinblastine, methods for the synthesis of both vindorosine (43) and vindoline from members of the quebrachamine and vincadifformine groups have been extensively investigated. The first results 

Reagents i, NaBHaCN, AcOH il, flow thermolysis at 400°C ill, KMhOa, MeCOMe, HCIO4 iv, m-CPBA, Fe, then SO2 v, saponification vi, decaitoxylation. 

The synthesis of vindoline (44) from 11-methoxytabersonine (82) is hampered by the lack of availability of starting material. Hence, Danieli et al. (253) have developed a method for the conversion of the much more abundant tabersonine into 11-methoxytabersonine and thence into vindoline. Since electrophilic substitution in tabersonine and 2,16-dihy-drotabersonine could not be effected cleanly and efficiently, IV-acetyl- 

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