Parsonsia heterophylla

Five new pyrrolizidine alkaloids, each containing a novel fourteen-membered macrocyclic ring, have been isolated by Edgar et al.x Parsonsine (44) and heterophylline (45) were present in Parsonsia heterophylla A. Cunn. and P. spiralis Wall., while spiraline (46), spiranine (47), and spiracine (48) were obtained only from P. spiralis. These five alkaloids are derived from retronecine that is esterified at C-9 with (-)-trachelanthic acid i.e. indicine), and further diesterified by a series of substituted malic acid derivatives to complete the fourteen-membered ring. Indeed, partial hydrolysis of parsonsine (44) yielded indicine (49). The non-equivalence of the C-9 protons (ABq, S 4.45 and 5.20 p.p.m.) in parsonsine indicates the presence of a macrocyclic system, and... 

Eggers, N. J., and Gainsford, G. J. (1979). Parsonsine (C22H33NOg) A pyrrolizidine alkaloid from Parsonsia heterophylla A. Cunn. Cryst. Struct. Commun. 8, 597-603. 

Edgar, J. A., N. J. Eggers, A. J. Jones, and G. B. Russell Unusual Macrocyclic Pyrrolizidine Alkaloids from Parsonsia heterophylla A. Cunn and Parsonsia spiralis Wall. (Apocynaceae). Tetrahedron Lett. 1980, 2657. 

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