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The configuration of several alkylidenephthalimidines, formed by dehydration of 3-alkyl-3-hydroxyphthalimidines, has been established by nuclear magnetic resonance techniques. When the nitrogen substituent is alkyl or aryl the configuration is (E) but when hydrogen it is (Z). Isomerization was observed in the temperature range 60-140°.
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Ang et al. (1971) studied this question.
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