- A novel and practical synthesis of 3-unsubstituted indolizines
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A novel and practical procedure for the preparation of 3-unsubstituted indolizines by 1,3-dipolar cycloaddition was developed. The requisite pyridinium N-methylides were generated simply from the corresponding N-(carboxymethyl)pyridinium halides. In the presence of MnO2, electron-deficient alkenes, instead of alkynes or vinyl bromides, were used successfully as dipolarophiles. This general method features cheap reagents, simple workup procedure and gives the products in moderate to high yields (57-92%).
- Zhang,Liang,Sun,Hu,Hu
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- Iodine Mediated Base-Controlled Regio-Selective Annulation of 2-(Pyridin-2-yl)acetate Derivatives with Acrylic Esters for the Synthesis of Indolizines
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An iodine mediated base-controlled reaction between 2-(pyridin-2-yl)acetate derivatives and acrylic esters has been developed for the selective synthesis of 1,3-disubstituted indolizines and 1,2-disubstituted indolizines. A single-pot reaction of 2-(pyridin-2-yl)acetate derivatives and acrylic esters in the presence of CsOAc delivers 1,3-disubstitued indolizines, while KHCO3 promotes the formation of C3-iodo indolizines, which could be further de-iodinated in the presence of copper powder, affording 1,2-disubstituted indolizines via a sequential stepwise fashion. A plausible reaction mechanism involving radical process has been proposed for this reaction. Pd-catalzyed reaction of C3-iodo indolizines with aryl boronic acids has been described. (Figure presented.).
- Fang, Youlai,Li, Fei,Liu, Xiaolan,Pan, Weidong,Yang, Yuzhu
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