Copper-mediated oxidative [3+2]-annulation of nitroalkenes and pyridinium ylides: a general access to functionalized indolizines. Efficient synthesis of 1-fluoroindolizinesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 22 февраля 2019 г.
Аннотация:A general method for the synthesis of substituted indolizines by copper (II) acetate-promoted oxidative [3+2]-annulation of α-fluoronitroalkenes with in situ generated pyridinium ylides was developed. Application of the copper (II) acetate - 2,6-lutidine system opens efficient access to various 1-fluoroindolizines in up to 81% yield. Both electron-rich and electron-deficient nitroalkenes as well as different pyridinium and isoquinolinium salts can be involved in the reaction. Moreover, it was found that copper-mediated annulation is applicable for other α-substituted (alkyl, chloro, ester) nitroalkenes giving rise to the corresponding indolizines. First synthesis of monofluorinated [3,2,2]cyclazines was demonstrated via oxidative annulation of 3 unsubstituted fluoroindolizines with diethyl acetylenedicarboxylate.