Constitution and absolute configuration of meta,meta-bridged, strained biphenyls from Myrica nagi; X-ray analysis of 16-bromomyricanol

Authors:
  • MBM. J. Begley
    M. J. Begley
  • RCR. V. M. Campbell
    R. V. M. Campbell
  • LCL. Crombie
    L. Crombie
  • BTB. Tuck
    B. Tuck
  • DWD. A. Whiting
    D. A. Whiting
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Abstract
Chemical and spectroscopic studies lead to the [7,0]metacyclophane structures (2) and (3) for myricanol and myricanone, phenolic extractives from Myrica nagi. X-Ray analysis of the meta-bridged biphenyl, 16-bromomyricanol (nitromethane solvate), by the heavy-atom method, confirmed these assignments, and gave the absolute configuration of myricanol. The compound crystallises in the monoclinic space group P21 with Z= 2 in a unit cell of dimensions a= 6·02, ± 0·01, b= 17·34 ± 0·02, c= 11·22 ± 0·02 Å, and β= 98·4°± 0·2°; the structure was refined to R 0·057 for 1075 independent reflections. C.d. measurements suggest that myricanol prefers the same conformation in solution as in the crystalline state. The biphenyl nucleus in 16-bromomyricanol is deformed by meta,meta-bridging. Similar strain in myricanone (3) is relieved by rearrangement with Lewis acids to the ortho,meta-bridged ketone (13). The natural phenols may be biogenetically related to diarylheptanoids.