Question

Provide a plausible mechanism for the twofold nucleophilic acylation reaction

twofold nucleophilic acyl substitution Me C) C) 3% NI NH2 + Eto OEt C) two diastereomers if racemic amine used one diastereomer if enantiomerically pure amine used diethyl oxalate

Answer 1

In this reaction, amine group of acts as nucleophile Step I Attack of 1-phenylethanamine on carbonyl carbon of diethyl ethanedioate. It removes ethoxy group as ethanol Me OEt Eto NH OEt Et 1-phenylethanamine diethyl ethanedioate Me OEt OEt NH NH -EtOH ethyl oxo[ (1-phenylethyl)aminolacetate O-Et Step II : Second molecule of 1-phenylethanamine attacks on second carbonyl carbon of diethyl ethanedioate to form our product. OEt H2N NH Me NH Me NH NH -O-Et CH3 NH CH Me O-Et Me NH NH NH -EtOH CH NH CH3 N,N-bis(1-phenylethyl)ethanediamide

If we use racemic mixture the product will be, Me NH NH NH CH3 NH CH3 N,N-bis[(1S)-1-phenylethyl]ethanediamide N-I(1R)-1-phenylethyl]-N-[(1S)-1-phenylethyljethanediamide If we use enantiometrically pure amine then the product will be, Me NH NH CH3 N,N-bis[(1R)-1-phenylethyl]ethanediamide OR NH NH CH N,N-bis[(1S)-1-phenylethyllethanediamide These both are same