Quinolizidines. XXVII. : Racemic and Chiral Syntheses of the Neisosperma and Ochrosia Alkaloid Ochropposinine

Tozo FUJII; Masashi OHBA; Takeshi TACHINAMI; Hisae MIYAJIMA

doi:10.1248/cpb.38.1200

Tozo FUJII, Masashi OHBA, Takeshi TACHINAMI, Hisae MIYAJIMA

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Keywords: Neisosperma alkaloid, Ochrosia alkaloid, ochropposinine, indoloquinolizidine alkaloid synthesis, chiral synthesis, lactim ether alkylation, keto amide cyclization, oxazolium salt reduction, Bischler-Napieralski cyclization, hydride reduction

JOURNAL FREE ACCESS

1990 Volume 38 Issue 5 Pages 1200-1204

DOI https://doi.org/10.1248/cpb.38.1200

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Abstract

The first total synthesis of ochropposinine (1), a Neisosperma and Ochrosia alkaloid, has been accomplished in the form of a racemic modification by means of an initial coupling of the lactim ether (±)-3 with 5 and succeeding steps proceeding through the intermediates (±)-7, (±)-8, (±)-9, (±)-10, and (±)-11. A parallel synthetic route starting with (+)-3 produced the chiral target molecule (-)-1 via the intermediates (+)-7, (+)-8, (+)-9, 10, and (-)-11. As a result, the absolute configuration of ochropposinine has been unequivocally established to be that represented by formula (-)-1.

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