The synthesis of 1-methyl-16demethoxy- carbonyl-20-desethylidenevobasine

✍ Scribed by Shun-Ichi Yamada; Takayuki Shiori

• Publisher: Elsevier Science
• Year: 1967
• Tongue: French
• Weight: 243 KB
• Volume: 8
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)71549-8

✦ Synopsis

We wish to communicate the first synthesis of l-methyl-16-demethoxycarbonyl-20-desetbylidenevobaeine(1) having the carbon skeleton of the P-acylindole alkaloids which are repreeented by vobad.ne(II)(l). I : B=CHJ, Br=H, &=H,H I1 : R=H, B1=COnCH3, B2=&HC& Catalytic hydrogenation of N-bensylidenetryptophan methyl ester(IIIa) (2,3) and its l-methyl derivative(IIIb) with platinum oxide in methanol afforded respectively N-benzyltryptophan methyl ester(IVa, hydrochloride: m.p. 188°(decomp.)) and its l-methyl derivative(IVb, hydroohloride: m.p. 232-233'(decomp.))(4) ti nearly quantitative yield. The Schotten-Baumann reaction of the eetera(IVa,b) with methyl 3-(chloroformyl)propionate gave the dimethyl eaters(Va: m.p. 135-135.5', Vb: viscous ofi(4)), which were respectively subjected to the Dieckmann cyclization reaction with sodium hydride in hot dioxane to give the methyl p-keto-eeters(VIa: m.p. 144-145',