School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China.
J Org Chem. 2011 Jul 15;76(14):5531-8. doi: 10.1021/jo200110w. Epub 2011 Jun 21.
A series of novel heterocyclic homotriptycenes bearing furan, thiophene, and pyridine rings, 7a-f, were synthesized by intramolecular dehydration reactions of 10,10-dihetarylmethyl-9,10-dihydroanthracen-9-ols 6a-f. In the presence of acids, the secondary alcohols 6a-f show different reactions which depend on the electron densities of the attached heterocyclic rings. The initially formed carbenium ions react in an electrophilic substitution with electron-rich heterocycles. The formation of a transannular bridge (1,7-elimination) leads to homotriptycenes in high yields. When the heterocyclic ring has a moderate electron density, two competitive reactions exist, which afford 9-monosubstituted anthracenes by 1,4-elimination or 9,10-disubstituted anthracenes by a rearrangement, respectively. Electron-deficient heterocycles undergo a disproportionation to give hydrocarbons and ketones.
一系列新型杂环同三苯并[cd,pq]苝衍生物 7a-f 通过 10,10-二取代甲基-9,10-二氢蒽-9-醇 6a-f 的分子内脱水反应合成。在酸的存在下，仲醇 6a-f 表现出不同的反应，这取决于所连接的杂环的电子密度。最初形成的碳正离子以亲电取代反应与富电子杂环反应。形成桥环（1,7-消除）以高产率得到同三苯并[cd,pq]苝。当杂环具有适度的电子密度时，存在两种竞争性反应，分别通过 1,4-消除得到 9-单取代蒽或通过重排得到 9,10-二取代蒽。缺电子杂环发生歧化反应生成烃和酮。
