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Synthesis of vinca alkaloids and related compounds, 73. Synthesis and ring transformations of deethylaspidospermane derivatives. Synthesis of (±)-20-deethyl-3-oxotabersonine

✍ Scribed by Kalaus, György ;Juhász, Imre ;Greiner, István ;Kajtár-Peredy, Mária ;Brlik, János ;Szabó, Lajos ;Szántay, Csaba

Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
823 KB
Volume
1995
Category
Article
ISSN
0947-3440

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✦ Synopsis

Abstract

The reaction of the key compound 14 with methyl 4‐formyl‐butanoate (9) or with 5‐benzoyloxypentanal (13) gave the D‐seco‐aspidospermane derivatives 17 and 18, respectively. Compound 17 was indirectly and 18 was directly converted to (±)‐20‐deethylvincadifformine (7) and (±)‐20‐deethyl‐20‐epivincadifformine (8). Epimerization occurred in both cases. The thioxo compound 23 was used for the synthesis of (±)‐20‐deethyltabersonine (28) and (±)‐20‐deethyl‐3‐oxotabersonine (27). Oxidative ring transformation of the (±)‐20‐deethylvincadifformine (7) gave (±)‐16‐deethylapovincamine (29).

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Synthesis ofVinca alkaloids and related
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## Abstract A versatile method for introducing a functionalized side chain into enamines 9a and 11a is described. This procedure provides an easy access to 16‐deethyl‐vincamines 16, 17 and 16‐deethyl‐apovincamines 18–21.

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Reaction or the enaminc 5 with u-bromoacryljc esters or achloroacrylonitrilc and subsequent reduction with NaBH4 yielded the pcntacyclic i>-noreburnamenine derivatives 8-10 or I 1 -14. rc-i f k r die Syatbesu voa Vinca-Alkaloiden uod vemandten Vcrbindungen, XXXVI". -Eine eiofacbe Syntbese einiger u-