| Summary: | 博士 === 國立交通大學 === 應用化學研究所 === 84 === Diels-Alder reaction of the cis-isomer 2b with cyclopentadiene in various media are investigated. In β-CD aqueous solution, the endo/exo ratio can be increased up to 99:1.
Diels-Alder reaction of the trans-isomer 3 with cyclopentadiene gave the cycloadducts 6 and 7, which stereochemistry was confirmed by chemical transformations such as reaction and iodocyclization reaction. Iodocyclization of 7b and 7c gave the methylthio group rearranged products 25b and 25c, which structure was proven by X-ray analysis of the crystalline compound 25b.
Diels-Alder reaction of 3 with cyclopentadiene in the presence of Lewis acids at -78 ℃ gave the endo-acyl product 6 exclusively.
Diacetal trioxa-cages where synthesized from norbornene derivatives of 2,3-bis-erirfo-γ-keto thioesters, 2,3-bis-endo-γ-keto esters and 2,3-bis-endo-l,4-diones by utilizing a novel sequential iodocyclization reaction as the key step. The structure of the trioxa-cages was proven by X-ray analysis of the crystalline compound 36.
The unsubstituted (parent) compound of trioxa-cages 55 was synthesized from the cyclopentadiene maleic anhydride cycloadduct 51 in a short sequence.
Dioxa-cage compounds were synthesized from the Diels-Alder cycloadducts of 1,4-benzoquinones with cyclopentadiene and cyclohexadiene in a short sequence via reduction with NaBH4-CeCl3, iodocyclization reaction, followed by treatment with KH in dryTHF.
Treatment of compounds 74 and 98 with KH in dry THF gave compounds 76 and 106 whose structures are tentatively assigned. The structure of 76 and 106 need to be confirmed by futher chemical proof.
Diels-Alder reaction of 1, 4-benzoquinone with two equivalents of cyclopentadiene 86 was synthesized from 81 via reduction with NaBH4 and iodocyclization reaction.
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