Σύνθεση και μελέτη χημικής συμπεριφοράς υδροξυ- και αμινο-τριπτυκενοκινονών και άλλων κινονικών παραγόγων

Abstract

The synthesis and chemical reactivity of certain hydroxy- and amino-quinones are studied in this work. Quinones consist an interesting class of compounds with diverse chemical and physical properties. Their chemistry is dependent on the substituents of the quinonic or the adjacent rings. Hydroxy- and amino- quinones that have one or more hydroxy or amino groups on the quinone moiety are found in nature and often possess various biological activities. The preparation of hydroxy-benzoquinone and hydroxy-napthoquinone derivatives and their iodonium dipoles through reaction with PhI(OAc)2 is described in the first chapter. These dipoles, through a Wolff rearrangement, are thermally converted to cyclopentenediones. The benzoquinone derivatives synthesized were: 2-hydroxy-5-chloro-p-benzoquinone (377), 2-hydroxy-5-methoxy-p-benzoquinone (388), 2-hydroxy-3,6-dimethyl-p-benzoquinone (393). Best results are obtained with electron-donnating groups, as electron-withdrawing groups do not favor the formation of hydroxy-quinones. The synthesis of 2-hydroxy-5-nitrovinyl-p-benzoquinone was unsuccessful probably due to the strong electron-withdrawing substituent on the quinone ring. The unexpected thermal stability of the iodonium dipole prepared from 2-hydroxy-5-boutyryl-p-benzoquinone (381) can be attributed to the carbonyl group which stabilizes the C-I bond of the iodonium dipole. Consequently, instead of the usual Wolff rearrangement, migration of Ph to the neighbor oxygen atom is observed. The failure to obtain 4-hydroxy-tricyclo[6.2.1.02,7]undece-2,4,9-triene-3,6-dione (407) can be explained by its unstable tricyclic structure which even in room temperature undergoes a retro-Diels-Alder reaction. The synthesis of heterocyclic 2-hydroxy-quinolino-quinone (417) was achieved by different methods, albeit in low yield and thus forbidding further reactions with synthetic interest. In the second chapter, triptycene, bearing an attractive rigid framework and being a molecule of interest since its one-step synthesis from Wittig, is combined with the hydroxy-quinone moiety. The study begins with the synthesis and chemical reactivity of 2-hydroxy-triptycene-quinone (474), the corresponding iodonium dipole (475) and cyclopentenedione (476). In section 2.2.B the cyclization reactions of hydroxy-quinone (474) and iodonium dipole (475) with alkynes are studied. Only the iodonium dipole affords furan cyclization products while the hydroxy-triptycene-quinone leads to unidentified mixtures. In section 2.2.Γ, Diels-Alder reactions of triptycene-cyclopentenedione (476), with non-cyclic dienes afforded polycyclic products. Similar reactions with cyclic dienes didn’t give products at all probably due to steric hindrance. In section 2.2.Δ, the dipole cycloadditions of the triptycene-cyclopentene-dione (476) are studied. Nitriloxides prepared in situ afforded tricyclic heterocyclic derivatives such as 493, 494.