Indolizines by a Consecutive 3CR of Acid Chlorides, Alkynes, and Pyridinium Ylids

2 Indolizines by a Consecutive 3CR of Acid Chlorides, Alkynes, and Pyridinium Ylids 

Indolizine is an aromatic 1 On-electron system and constitutional isomer of l-H indole and, consequently, has received a considerable theoretical and practical interest [100]. Considering the well-established fluorescence properties of indolizines [101-103] and biindolizines [102], and the steadily increasing importance of fluorophores in biolabeling and environmental trace analysis, we have been seeking for a new, efficient synthesis of fluorescent indolizines. Two general ways of indolizine syntheses have been known so far [100]. The first route is based on the intramolecular formation of the indolizine by cyclocondensation of suitable pyridinium precursors. However, the second approach takes advantage of a [3 + 2] 

The just discussed sequence is another methodological showcase for the combination of cross-coupUng and cycloaddition in the same reaction vessel, giving rise to a broad variety of indolizines 26. In particular, 7-(pyridin-4-yl)-substituted 

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