Halfordia Alkaloids

Natural product o-methylhalfordinol 117 is a basic principle of the oxa-zole alkaloids of Halfordia scleroxyla and Aegle marmelos. Annuloline 119, a blue fluorescent pigment, has been isolated from the roots of rye stalk Lolium multifiorum. The total synthesis of 2,5-disubstituted oxazole alkaloids o-methylhalfordinol and annuloline is based on the aza-Wittig reaction (Scheme 48). Thus 4-methoxyphenacylazide 115, triphenylphos-... 

In the oxazole-containing species recognized thus far, anthranilate is evidently not always shunted into nicotinate formation as some of these taxa accumulate products attributable to a more direct utilization of anthranilate. Halfordia ken-dack contains the quinoline alkaloid halfordamine (55) and the furanoquinoline halfordinine (56) (8, 22), while small quantities of dictamnine (57) occur in H. 

Halfordia scleroxyla F. Muell. and H. kendack (Rutaceae) (ref. 33b, p. 565) Details concerning the structural elucidation of the pyridine-oxazole alkaloids (14) have been reported. Interestingly, furoquinolines are found in the same plant species. 

The minor alkaloid of this plant, provisionally named aegelenine, was shown to be identical with halfordinal previously obtained from Halfordia sderoxyla F. Muell. (3). 

Halfordinine, found earlier in Halfordia scheroxyla, clearly was a trimethoxydic-tamnine, but its constitution was not established. The alkaloid has since been isolated from Melicope perspicuinervia and shown to be 6,7,8-trimethoxydictamnine... 

Halfordinine, C15H15N05, a minor component of the bark of Halfordia scleroxyla, was isolated by Crow and Hodgkin (22). There was insufficient material for a full structural investigation, but the alkaloid was shown to be a trimethoxydictamnine on the basis of the NMR spectrum. Halfordinine (mp 150-151°) clearly was not identical with 5,7,8-trimethoxydictamnine (acronycidine) (mp 136-137°). Halfordinine has been obtained recently from the leaves of Melicope perspicuinervia Mer. and Perry. Murphy, Ritchie, and Taylor (42) noted that the NMR signal at t2.69 indicated that... 

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