Daffodils, King Alfred

In 1956, the alkaloid Methylpseudolycorine (101) isolated from the King Alfred daffodil (Narcissus pseudonarcissus L.) was oxidized to the pale yellow chloride with selenium dioxide (Scheme 36). Conversion into the betaine was accomplished by aqueous ammonia to give yellow prisms of the trihydrate of Criasbetaine (100) (56JA4145, 56JA4151). The UV absorption... 

Feeding experiments with doubly labeled 3-hydroxy-4-[14C]methoxy-A-meth-yl-(f -[3H]- and -(5)-[3H]A,-benzylamines in King Alfred daffodils produced oduline (186) with high (82-85%) tritium retention (139). This observation suggested that the incorporation of A-methylisovanillamine into 186 occurred by a nonstereospecific process in which hydrogen removal from the benzylic position was governed by a kinetic isotope effect. 

The two enantiomeric precursors, when mixed with identical relabeled samples, were fed to King Alfred daffodil. High 3H retention (ca. 66%) was observed in haemanthamine with the (2 ) isomer 417, whereas 30% was detected for the (2R) isomer 418. Oduline (109) completely retains the 3H labels in both feedings. 

Conflict exists in deciding on the stereochemical course of the hydroxylation at C-2 of, e.g., norpluviine (100), which leads to lycorine (104). One set of results indicates that hydroxylation occurs with normal retention of configuration82 whereas the other set, obtained in a different plant, indicates that the reaction occurs with unusual inversion of configuration.83 The conversion of [2/8-3H, 9-OMe - 14C]pluviine [as (101)] into galanthine (103), in King Alfred daffodils, with retention of 79% of the tritium label confirms that the hydroxylation of C-2 may occur with inversion of configuration.80... 

Although norbelladine was shown not to be a precursor of galanthamine (101) in King Alfred daffodils, an incorporation of this compound with labels as shown (103), comparable to that for lycorine (104), has been obtained for galanthamine in Leucojum aestivum As expected, the lycorine showed loss of half its tritium. On the other hand, no loss of tritium was apparent in the galanthamine. The latter result suggested that in the biosynthesis of galanthamine conversion of (105) to narwedine (100) was either not reversible or, if so, enzy-mically controlled. 

Methylpseudolycorine was isolated in trace amounts from the bulbs of the King Alfred daffodil by Fales and associates (93). The alkaloid, Ci7HjiiN04, contains two methoxyls and two vicinal, nonenolic hydroxyls, but no. V-methyl function. Catalytic hydrogenation afforded dihydromethylpseudolycorine. Spectral and basicity measurements indicate that this double bond is not a,)S to the nitrogen atom or conjugated with the aromatic ring. 

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