The Investigation of the reactivities of biceyclic systems containing exzocyclic diene against dienophiles and the synthetic reactivity of the products formed

11 THE INVESTIGATION OF THE REACTIVITIES OF BICYCLIC SYSTEMS CONTAINING EXZOCYCLIC DIENE AGAINST DIENOPHILES AND THE SYNTHETIC REACTIVITY OF THE PRODUCTS FORMED (Ph. D. Thesis) Recep ÖZEN GAZİ UNIVERSITY INSTITUTE OF SCEENCE AND TECHNOLOGY December 2000 ABSTRACT 2,3-Bis(methylene)-7-oxabenzonorbornene was synthesized starting from 7- oxabenzonorbornene (18). For the synthesis of (14), a new synthetic strategy was devoloped. The key compound l,4-epoxy-l,2,3,4-tetrahydronahthalene- ejc0-ds-2,3-dicarboxylate (17) was obtained by the methoxycarbonilation of 18. Reaction of singlet oxygen with diene 14 resulted in the formation of monocyclic endoperoxide 11. CoTPP catalyzed rearrangement of 11 gave isomeric bisepoxide mixture 147, 148, 149 and hydroxy-aldehyde 150 instead of furan (12). The products were isolated and characterized. The formation mechanism is discussed. To study the formation mechanism of this isomeric mixture in more detail we synthesized the 2,3-dimethylenenorbornan (27) as reported in the literature. The reaction of 27 with singlet oxygen provided expected product endoperoxide 82. CoTPP catalyzed rearrangement of 82 gave a mixture of isomeric bisepoxides 83, 85, 155 and major product hydroxy-aldehyde 84. In presence of AcOH Ac20 84 was converted to furan 85. Hydroxy-aldehyde 150 was olso subjected to acid catalyzed reaction. Unfortunatelly all attempts were failed to cyclisize this compound. Dienes 5, 6, 14, 27 reacted with dienophiles such as 7-oxabenzonorbornadiene (18) and benzonorbornadiene (28) afforded [2+4] Diels-Alder adduct products 19, 21a, 21b, 23a, 163, 166, 167 were obtained respectivelly. Science Code Key Words Page Number Adviser 405. 02. 01 Exzocyclic dien, Diels-Alder reaction, Singlet oxygen 111 Prof. Dr. Metin BALCI, Prof. Dr. Basri ATASOY