Publication details
Acidified Alcohols as Agents to Introduce and Exchange Alkoxyls on the Periphery of Helicenes
| 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; alkoxyl; diastereomer; separation |
| Description | Alcs. contg. HCl transform the hydroquinone redn.-products of helicenebisquinones into p-alkoxyphenols that have the alkoxyls specifically on the peripheries of the helixes. The reactions are quick, and the yields are high. Alkoxyls at the 6-position are replaced also, but only after 2 h at 60 C, not after the 5 min at 25 C sufficient to replace the peripheral hydroxyls of the hydroquinones. After the remaining inside hydroxyls of a dihydroxytetramethoxy[6]helicene prepd. by this procedure were converted into camphanates, one diastereomer crystallizes from soln., allowing an enantiomer resoln. to be carried out on a large scale. By then simply re-applying the procedure with alc. acid, a variety of resolved dihydroxytetraalkoxy[6]helicenes can be prepd. in excellent yields without resoln. procedures having to be developed for each. Similar procedures are effective when applied to a [7]carbohelicene. |