提出了一种由6-取代的3-硝基-2-吡啶酮制备吡啶并[2,3- b ] [1,4]恶嗪的新方法。该方法包括两个步骤:O-烷基化和还原环化。在前一步中,发现硝基吡啶酮和C2试剂的庞大体积对于避免N-烷基化至关重要,因为N-烷基化会有效地进行O-烷基化。随后的还原环化作用提供了在2和6位上都没有碳取代基的吡嗪并嗪。
The ring transformation of nitropyrimidinone 1 with acetophenone derivatives 2 affords two kinds of azaheterocyclic compounds, 4-phenylpyrimidines 3 and 3-nitro-6-phenyl-2-pyridones 4. On the basis of the relationship between electronic properties of the substituent and ratios of products, a plausible reaction mechanism is provided. Furthermore, the present reaction could be applied to heterocyclic ketones giving bihetaryl compounds.
Mechanistic aspect of ring transformations in the reaction of 5-nitro-4-pyrimidinone with acetophenone derivatives and cycloalkanones depending on the electron density/ring size of the ketone
idinone undergoes two kinds of nucleophilic type ring transformations upon treatment with cycloalkanones in the presence of ammonium acetate, which affords 4,5-disubstituted pyrimidines and 5,6-disubstituted 3-nitro-2-pyridones. In order to improve the synthetic utility of this reaction, it is necessary to control the regioselectivity of these ring transformations. In the present work, we performed