The structure of the bisbenzylisoquinoline alkaloid methylwarifteine

Abstract

The crystal structure of the bisbenzylisoquinoline alkaloid methylwarifteine, C37HasN206, has been determined by direct methods, using Cu K tq diffractometer data. The compound crystallizes in the orthorhombic space group P2~2~21, with unit-cell dimensions a = 17.539 (4), b = 12.224 (3), c = 14.393 (3) A, Z = 4. The structure was refined by full-matrix least-squares methods to R = 0-057, for 2508 observed reflections. The phenyl rings of the isoquinoline groups are planar and the nitrogen-containing rings are both in similar half-chair conformations, with the pseudo twofold axis bisecting two C-C bonds. The benzyltetrahydroisoquinoline residue is in an extended conformation while the benzyldihydroisoquinoline residue is folded. The two halves of the molecule thus formed are joined by an ether linkage on one side and a methoxy linkage on the other side. The dihedral angle between the two benzyl groups is 111.3 o.

The structure of the bisbenzylisoquinoline alkaloid dimethylwarifteine

“…and 1.51 A in (+)-tubocurarine dibromide (Reynolds & Palmer, 1976). The C--N double bond in the 3,4-dihydroisoquinoline ring E is 1.288 (13)A, in good agreement with the value of 1.292 (7)A found in methylwarifteine (Borkakoti & Palmer, 1978). The average N-C-C angle for ring B is 112.5 °, which compares well with the value 111.4 ° obtained for tetrandrine (Gilmore, Bryan & Kupchan, 1976) ;,4 c5 c2 _:----.--_ c23 Fig.…”

The structure of tetrazole steroid analogues. I. The structure of 17β-(5-methyltetrazol-1-yl)-7a-aza-B-homoandrost-5-eno[7a,7-d]tetrazol-3β-yl acetate (HS-665)

“…Of the five C-N bonds in the molecule only one, the linkage bond C(17)-N(I") = 1.466 (5)A between rings D and T 2, is a true single bond. This value compares well with the average C-N bond length of 1.475 (4)A in the alkaloid methylwarifteine (Borkakoti & Palmer, 1978). The average of the four other ring C-N bond lengths is 1.334 A, all being within 2o of this value.…”

Warifteine and methylwarifteine: 1H and 13C assignments by two‐dimensional NMR spectroscopy

“…The complete structure of 2 was later verified by x-ray crystallography. 5 Since the relative positions of the OH and OMe groups on each ring cannot be determined with certainty from mass spectra alone, the earlier study 1 tentatively assigned the two free phenolic OH groups of 1 to rings A and F and the free phenolic group of 2 to ring F; however, the regiochemistry of the phenolic and methoxyl substituents of 1 was never completely determined. In this study, we chose to make these assignments by using NMR spectroscopy.…”

“…3 In addition, cissampareine was found to be isomeric with methylwarifteine and had the same skeleton since both gave dimethylwarifteine on permethylation. Since the relative positions of the OH and OMe groups on each aromatic ring of the two isoquinoline moieties were never defined, the structure of the most abundant alkaloid of C. ovalifolia, warifteine, remained unsettled even though the x-ray crystal structures of both dimethylwarifteine 4 and methylwarifteine 5 were determined. We remained interested in elucidating the complete structures of warifteine and methylwarifteine since publishing a review on bisbenzylisoquinoline alkaloids, 6 where warifteine and cissampareine were placed in a special section with one diphenyl ether and one benzyl phenyl ether linkage.…”