Ureas are often thought of as "double amides" due to the obvious structural similarity of these functional groups. The main structural feature of an amide is its planarity, which is responsible for the conjugation between the nitrogen atom and carbonyl moiety and the decrease of amide nucleophilicity. Consequently, since amides are poor nucleophiles, ureas are often thought of as poor nucleophiles as well.
View Article and Find Full Text PDFThe cooperative L-proline/Brønsted acid/base promoted reaction of 2-ethoxypyrrolidines or -substituted 4,4-diethoxybutan-1-amines with methyl(alkyl/aryl)ketones for the synthesis of 2-(acylmethylene)pyrrolidine derivatives is reported. The key features of the developed protocol are gram-scale synthesis of the target compounds, easily available starting materials, operational simplicity and usage of non-expensive reagents.
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