Beilstein J. Org. Chem.2011,7, 1323–1326, doi:10.3762/bjoc.7.155
trifluoroacetic anhydride followed by decomposition of the reaction mixture in methanol under reflux yielded 1,3-cyclohexandione in 25% yield. Later, Smit and coworkers reported the closely related acyclic reaction between alkynes and acyl cations leading to β-diketones in 25–76% yield [8][9]. Interestingly, only
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Graphical Abstract
Scheme 1:
3-Alkoxy-2-cyclohexenones from the cyclization of 5-hexynoyl chloride.
Beilstein J. Org. Chem.2010,6, No. 11, doi:10.3762/bjoc.6.11
+ POCl3) using excess phosphorous oxychloride as solvent following our published method [51]. The nucleophilic substitution of the chloro group of 1 by allyl amines 2 afforded the 6-N-allyl-1,3-dimethyl-5-formyl uracils 3. Compounds 3 were then reacted with cyclic β-diamides/β-diketones 4 in presence of a
3a as a yellow solid 568 mg (95%). Similarly, 3b–c were prepared from the reaction of 1 with 2b–c.
Knoevenagel condensation of 3 with cyclic β-diamide/β-diketones 4 and synthesis of 5: Equimolar amounts of 3a (2 mmol, 598 mg) and 4a (2 mmol, 312 mg) were mixed thoroughly in a round-bottomed flask
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Graphical Abstract
Scheme 1:
Stereoselective synthesis of some new complex annulated pyrido[2,3-d]pyrimidines by intramolecular ...