STEREOSELECTIVITY IN THE CYCLO-ADDITION REACTIONS OF 2-ETHOXY-3-METHYLISOQUINOLINIUM SALTS
STEREOSELECTIVITY IN THE CYCLO-ADDITION REACTIONS OF 2-ETHOXY-3-METHYLISOQUINOLINIUM SALTS
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DOI：
10.1021/jo00393a044
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发表时间：
1979-01-01
影响因子：
3.6
通讯作者：
BRADSHER, CK
中科院分区：
文献类型：
--
作者：
CHEN, TK;BRADSHER, CK
与苯乙烯、异戊二烯和环戊二烯，2-乙氧基-3-甲基异喹啉离子及其5-硝基衍生物比它们的2-甲基对应物更容易进行极性环加成。这些环加成的特征是立体选择性，在许多情况下为100%，并且在几乎所有情况下被认为具有极性来源。2，3-二甲基异喹啉鎓盐（1）将与烷基乙烯基醚或环戊二烯进行区域选择性和立体选择性的1，4-加成的发现2”5具有理论意义，但由于反应性较低的烯烃（例如苯乙烯）在任何试验条件下都不能反应。结果表明，如果在5位引入硝基，异喹啉鎓盐的反应活性可大大提高（参见文献[1]）。2），允许与相对未活化的烯烃如β-蒎烯或异蒎烯反应。6早期的观察结果7，8提出了一种有希望的替代方法，即2-烷氧基异喹啉鎓盐显示出高的
With styrenes, norbornenes, and cyclopentadiene, 2-ethoxy-3-methylisoquinolinium ion and its 5-nitro derivative undergo polar cycloaddition more readily than do their 2-methyl counterparts. Characteristic of these cycloadditions is a stereoselectivity which in many instances is 100% and which in nearly all instances is believed to have a polar origin.The discovery2" 5 that 2, 3-dimethylisoquinolinium salts (1) will undergo 1, 4-addition both regioselectively and stereoselectively with alkyl vinyl ethers or cyclopentadiene was of theoretical interest but of limited synthetic value since less reactive alkenes (eg, styrene) failed to react under any of the conditions tried. It was demonstrated that the reactivity of the isoquinolinium salt could be greatly enhanced if a nitro group was introduced at pos-ition 5 (cf. 2), permitting reaction with such relatively unactivated alkenes as/3-pinene or norbornene. 6 A promising alternate approach was suggested by earlier observations7, 8 that 2-alkoxyisoquinolinium salts show high