| Abstract
| - A procedure is described for synthesizing appreciable quantities of both the tetradodecyloxy[6]helicenebisquinone 1 (R = dodecyl), which exhibits unique optical properties but previously wasdifficult to prepare, and a variety of analogues. The synthesis starts from disodium 4,5-dihydroxynaphthalene-2,7-disulfonate, the commercially available dye-intermediate known aschromotropic acid. It gives enantiopure 1, with R = (i-Pr)3Si, whose silyl groups can be replaced bydodecyl and hexanoyl groups. The same procedure applied to disodium 4-hydroxynaphthalene-2,7-disulfonate, also an inexpensive, commercially available chemical, works equally well to producethe corresponding molecules that have one fewer side chain. Key steps are the use of tosyl groupsto protect phenols and of a method described seven years ago by Satoh, Itoh, Miura, and Nomurato transform the sulfonic acid functions to iodides. The structure of tetra-(1S)-camphanate 20, theester of the reduction product of (−)-1 [R = (i-Pr)3Si], was analyzed by X-ray diffraction. It showsthe absolute configurations and supports the presumed basis for the rule that the (1S)-camphanatesof (P)-helicen-1-ols are more polar than their (M)-diastereomers.
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