扶喃二烯-丙二烯醚基之分子內 Diels-Alder 反應之研究(六)

Abstract

為了探討扶喃環上引進不同雜異原子之取代基對分子內Diels-Alder反應 的影嚮,將扶喃環5的位置上由甲硫基變換成甲亞磺醯基後進行分子內 Diels-Alder反應,得到另一新奇反應之產物是甲亞磺醯基之1,2-重排反應 的產物(14)至(18),而沒有得到1,4-重排反應的產物.再將甲硫基變換成甲 磺醯基後進行分子內Diels-Alder反應,除了得到甲磺醯基之1,2-重排反應 的產物(25)至(29)外,另有微量的甲磺醯基之脫去反應的副產物(26b).再 將扶喃環5的位置上由甲硫基變換成苯硫基後進行分子內Diels-Alder反 應,同時得到苯硫基之1,2-重排反應的產物(35a).(36a)及(37a)和1,4-重 排反應的產物(35b).(36b)和(37b).接著,再將扶喃環5的位置上引進三甲 矽烷基後進行分子內Diels-Alder反應,除了得到三甲矽烷基之 1,2-重排 反應的產物(46a)及(47)外,另有 Brooks' anionic 重排反應的副產物(46 b),不過這只是初步之結果,尚留待將來再繼續探討.由以上實驗結果中,在 扶喃環 5 的位置變換不同之官能基後進行分子內 Diels-Alder 反應,將 會有不同的重排反應發生. In order to study the effect of various hetero-substituents at the 5th position of the furan ring on the intramolecular Diels- Alder reaction, the furfuryl propargyl ethers with methylsulfinyl , methylsulfonyl, phenylthio and trimethylsilyl group at the 5th position of the furan ring were prepared for the cycloaddion. Thus, intramolecular Diels-Alder reaction of (9)-(13) with t-BuOK in t-BuOH gave the methylsulfinyl group 1,2-rearranged products (14)-(18) respectively. Intramolecular Diels-Alder reaction ofmethylsulfonyl compounds (20)-(24) under the same reaction condition gave the 1,2-rearranged products (25)-(29) respectively .In the case of compound (21), a small amount of by product (26b) with the sulfonyl group completely leaving was isolated. Intramolecular Diels-Alder reaction of the phenylthio compounds (32-1),(33-1)and(34) under the same reaction conditions gave both the 1,2-rearranged products (35a)-(37a) and the 1,4-rearranged products (35b)-(37b) respectively. Intramolecular Diels-Alder reaction of the trimethylsilyl compounds (44-1) and (45-1) under the same reaction conditions gave the 1,2-rearranged products (46a) and (47), and the Brook's anionic rearrangement product (46b), Futher studies on this reaction will be continued in our lab.. Thus, we found that different functional group at the 5th position of the furan ring gave different rearrangement products during the intramolecular Diels-Alder reaction.