title: Structures of perfragilin A and B.
abstract: The two perfragilins both have a similar backbone (an isoquinolinetrione skeleton) but differ in their substitution pattern at C(6) and C(7); perfragilin A has a thiomethyl group at C(6) and amide group at C(7), whereas perfragilin B has a thiomethyl group at both these positions. The effects of these substituents are reflected in the bond distances and bond angles, particularly in the benzoquinone segments of the molecules. The amide group in perfragilin A leads to a resonance structure and a planar isoquinoline ring system [r.m.s. deviation 0.026 (2) A]. The presence of the two thiomethyl groups in perfragilin B causes the isoquinoline ring system to exhibit significant deviations from planarity [r.m.s. deviation 0.067 (1) A].
authors.affiliation: Department of Chemistry and Biochemistry, Oklahoma University, Norman 73019.
authors.forename: S K
authors.initials: SK
authors.lastname: Rizvi
authors.forename: M B
authors.initials: MB
authors.lastname: Hossain
authors.forename: D
authors.initials: D
authors.lastname: van der Helm
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D007546:Isoquinolines / Q000737:chemistry*; D015394:Molecular Structure; D014961:X-Ray Diffraction
chemical_list: D016227:Benzoquinones; D007546:Isoquinolines; C080170:perfragilin A; C080172:perfragilin B