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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Synthesis of 6-arylpyrimido[4,5-e]indolizine-2,4(1H,3H)-diones through InCl3-catalyzed cycloisomerization
Ruben Manuel Figueira de Abreu1, Alexander Villinger1, Peter Ehlers1
1Universität Rostock, Institut für Chemie, Albert-Einstein-Str. 3a, 18059 Rostock, Germany. peter.langer@uni-rostock.
Abstract:
We report the synthesis of hitherto unknown pyrimido[4,5-e]indolizine-2,4(1H,3H)-diones (indolizinouracils) and related polycondensed uracils. The synthetic strategy is based on a chemoselective C-N coupling through an addition-elimination reaction of N,N-dimethyl-5-bromo-6-chlorouracil with N-heterocycles, followed by Sonogashira cross-coupling reaction with alkynes and InCl3-catalysed cycloisomerisation. The methodology allows for the employment of pyrrole and indole as N-heterocyclic building blocks and tolerates various functional groups. The impact of the substitution pattern on the photophysical properties was studied by steady-state UV-Vis and fluorescence spectroscopy, providing new insights into the potential applications of uracil-based polycondensed heterocycles.
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