Publication details
Expeditious Procedure To Synthesize Ethers and Esters of Tri- and Tetrahydroxy[6]helicenebisquinones from the Dye-Intermediates Disodium 4-Hydroxy- and 4,5-Dihydroxynaphthalene-2,7-disulfonates
| Authors | |
|---|---|
| Year of publication | 2000 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Organic Chemistry |
| MU Faculty or unit | |
| Citation | |
| Field | Organic chemistry |
| Keywords | helicene; Miura; preparation; optical properties |
| Description | A procedure is described for synthesizing appreciable quantities of both the tetradodecyloxy[6]helicenebisquinone I (R = dodecyl), which exhibits unique optical properties but previously was difficult to prep., and a variety of analogs. The synthesis starts from disodium 4,5-dihydroxynaphthalene-2,7-disulfonate, the com. available dye-intermediate known as chromotropic acid. It gives enantiopure I [R = (Me2CH)3Si] whose silyl groups can be replaced by dodecyl and hexanoyl groups. The same procedure applied to disodium 4-hydroxynaphthalene-2,7-disulfonate, also an inexpensive, com. available chem., works equally well to produce the corresponding mols. that have one fewer side chain. Key steps are the use of tosyl groups to protect phenols and of a method described seven years ago by Satoh, Itoh, Miura, and Nomura to transform the sulfonic acid functions to iodides. The structure of tetra-(1S)-camphanate II [R1 = (Me2CH)3Si; R2 = (1S)-camphanoyl], the ester of the redn. product of (-)-I [R = (Me2CH)3Si], was analyzed by X-ray diffraction. It shows the abs. configurations and supports the presumed basis for the rule that the (1S)-camphanates of (P)-helicen-1-ols are more polar than their (M)-diastereomers. |