Hunterburnine

The total crude alkaloids had hypotensive activity (31) traced largely to the quaternary bases (27), but the only pure active compound isolated was hunterburnine a-methochloride (28). 

Following earlier work, quinine has now been transformed into dihydro-hunterburnine a- and jS-methochlorides, " dihydroantirhine, " 10-methoxy-dibydrocorynantheol, and ochrosandwine. Scheme 5 depicts the formation of dihydrohunterburnine (36) and 10-methoxydihydrocorynantheol (37). These transformations establish the absolute configurations of the hunterburnine metho-salts, and of 10-methoxydihydrocorynantheol and ochrosandwine, and confirm that of antirhine. 

Hunterburnine a- and j8-methochlorides and huntrabrine metho-chloride have been isolated from the closely related plant, Pleiocarpa mutica Benth. (3d). The mass spectra of hunterburnine a- and /3-metho-chlorides have been studied along with other quaternary salts (31). Both... 

Hunterburnine a- and -Methochlorides. Similar to the case of bumamicine, the quaternary salts hunterburnine a- and j8-metho-chlorides were isolated from Hunteria ebumea in amounts which did not lend themselves to chemical examination and they were not volatile enough for mass spectrometric work. By physical methods they were recognized to be 5-hydroxyindoles, to contain a quaternary N-methyl and a vinyl group. Since their iodides were in a form suitable for X-ray analysis this appeared to be the method of choice for their structural elucidation which is discussed for the )3-methiodide. 

Hunterburnine -methiodide crystallized in the orthorhombic system space group P2i2i2i (a common one for natural products) with four molecules to the unit cell. Three dimensional X-ray... 

Hunterburnine a- and jS-methochlorides have turned out not only to be representatives of a previously unexpected combination of Type I precursor and tryptamine but also to be the first examples of naturally occurring epimeric quaternary salts. 

---