Imine formation is followed by cyclisation and this

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Unformatted text preview: e of the problem Extension of acetal and imine formation into examples where the intermediate is trapped by a different nucleophile. 5 6 Solutions Manual to accompany Organic Chemistry 2e Suggested solution The first reaction starts with the usual attack of an alcohol on the aldehyde but the second nucleophile is the carboxylic acid. Though a poor nucleophile, it is good enough to react with an oxonium ion, particularly in a cyclisation. O H OH HO CO2H O O OH OH OH O O O OH2 O O O O O OH O The second reaction starts with nucleophilic attack by the amine on the more electrophilic carbonyl group – the ketone. Imine formation is followed by cyclisation and this second step is normal nucleophilic substitution of an ester (chapter10). The imine double bond moves into the ring to secure conjugation with the ester. H 2N O NH2 N NH2 O CO2Me X H N H N H N HN O O OMe HH The third example uses very simple molecules and again starts with imine formation. Cyanide is the nucleophile that captures the iminium ion...
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This document was uploaded on 02/10/2014.

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