Nitrogen compounds depsipeptides

The isomerization with cleavage of the barbituric acid ring depends on substituents at the nitrogen atoms.272,406,407 Introduction of a benzoyl group into the 3-position of l-o-hydroxyphenyl-5,5-dipropylbarbituric acid enables this compound to isomerize to the correspondent depsipeptide (150), whereas l-o-hydroxyphenyl-3-phenyl-5,5-dipropylbarbituric acid does not isomerize.350,408... 

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