- Thermal cyclization of 1,2-dialkynylimidazoles to imidazo[1,2-a]pyridines
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Thermolysis of 1,2-dialkynylimidazoles in chlorinated solvents leads to 5-chloroimidazo[1,2-a]-pyridine products, which are also formed in DMF containing 1 equiv of HCl. Deuterium labeling of the starting dialkynylimidazoles indicates that reaction may proceed by multiple pathways, depending upon conditions and substituents. Dialkynylimidazoles can also give rise to 5-diethylamino-substituted imidazopyridines when the thermolysis is carried out in the presence of diethylamine.
- Nadipuram, Asha K.,Kerwin, Sean M.
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p. 3798 - 3808
(2007/10/03)
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- Synthesis and thermolysis of heterocyclic 3-aza-3-ene-1,5-diynes(1).
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[reaction: see text] Simple, acyclic 3-aza-3-ene-1,5-diynes undergo an aza-Bergman rearrangement to a fleeting 2,5-didehydropyridine (2,5-ddp) intermediate that rapidly ring-opens to beta-alkynylacrylonitrile products. In an effort to access longer-lived 2,5-ddp intermediates, we have prepared heterocyclic 3-aza-3-ene-1,5-diynes. The thermolysis of one such heterocyclic aza-enediyne does not afford products derived from trapping a 2,5-ddp intermediate but rather cyclopropanes that appear to arise from a carbene intermediate and a product that appears to be a trapping product from a 2,3-ddp intermediate.
- Nadipuram, Asha K,David, Wendi M,Kumar, Dalip,Kerwin, Sean M
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p. 4543 - 4546
(2007/10/03)
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