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Imines reactions with highly acidic active methylene

Reactions using highly acidic active methylene compounds (pAa = 9-13) comprise nearly all the early examples of imine condensation reactions, some of which date back to the turn of the century. Reviews by Layer and Harada have summarized many of these reactions and include examples using diethyl malonate, ethyl cyanoacetate, ethyl malonamide, acetoacetic acid, benzoylacetic esters and nitroalkanes. Conditions of these reactions vary they have been performed both in protic and aptotic solvents, neat, and with and without catalysts. Elevated temperatures are generally required. Reactions with malonates have useful applications for the synthesis of 3-amino acids. For example, hydrobenzamide (87), a trimeric form of the benzaldehyde-ammonia Schiff base, and malonic acid condense with concomitant decarboxylation to produce p-phenylalanine (88) in high yield (equation 14). This is one of the few examples of a Mannich reaction in which a primary Mannich base is produced in a direct manner but is apparently limited to aromatic imines. [Pg.916]


See other pages where Imines reactions with highly acidic active methylene is mentioned: [Pg.270]    [Pg.270]    [Pg.270]    [Pg.270]    [Pg.397]    [Pg.94]    [Pg.70]    [Pg.1294]    [Pg.31]   


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Activated imine

Activated methylene

High activities

High reactions

Imine reaction

Imines acids

Imines activation

Imines, reactions

Methylenation reaction

Methylene reactions

Methylenes, activated methylene

Reaction with imines

Reaction with methylene

With imines

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