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.
Quinolizidines. XXVII. Racemic and chiral syntheses of the Neisosperma and Ochrosia alkaloid ochropposinine
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