Methyl-substituted dispiro-1,2,4,5-tetraoxanes: Correlations of structural studies with antimalarial activity

Kevin J. McCullough, James K. Wood, Apurba K. Bhattacharjee, Yuxiang Dong, Dennis E. Kyle, Wilbur K. Milhous, Jonathan L. Vennerstrom

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

Two tetramethyl-substituted dispiro-1,2,4,5-tetraoxanes (7,8,15,16- tetraoxadispiro[5.2.5.2]hexadecanes) 3 and 4 were designed as metabolically stable analogues of the dimethylsubstituted dispiro-1,2,4,5-tetraoxane prototype WR 148999 (2). For a positive control we selected the sterically unhindered tetraoxane 5 (7,8,15,16-tetraoxadispiro[5.2.5.2]hexadecane), devoid of any substituents. Tetraoxanes 3 and 4 were completely inactive in contrast to tetraoxanes 2 and 5. We hypothesize that the two inactive tetraoxanes possess sufficient steric hindrance about the tetraoxane ring due to the two additional axial methyl groups to prevent their activation to presumed parasiticidal carbon radicals by inhibiting electron transfer from heme or other iron(II) species. For each of the tetraoxanes 2-4, the tetraoxane and both spirocyclohexyl rings are in a chair conformation and the bond lengths and angles are all quite normal except for the C1-C2 bond which is slightly lengthened. Comparison of the modeled and X-ray structures for tetraoxanes 2-5 reveals that molecular mechanics (MMX and MM3) and 3-21G* calculations each gave accurate structural parameters such as bond lengths, bond angles, and dihedral angles. In contrast, semiempirical methods such as AM1 gave poor results.

Original languageEnglish (US)
Pages (from-to)1246-1249
Number of pages4
JournalJournal of Medicinal Chemistry
Volume43
Issue number6
DOIs
StatePublished - Mar 23 2000

ASJC Scopus subject areas

  • Molecular Medicine
  • Drug Discovery

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