The reactivity of N-tert-butyloxycarbonyl-N-carboxyanhydrides derived from �-alanine, (S)-�3-homophenylglycine and (S)-�3-carboxyhomoglycine with different a- and �-amino ester hydrochlorides was examined under ball-milling activation. In particular, good to excellent yields of several relevant a,�- and �,�-dipeptides were obtained. An illustrative application of this methodology consisted in the high-yield synthesis of the mammalian a,�-dipeptide N-Boc-L-carnosine-OMe.The organocatalytic activity of the methyl ester of (S)-proline-(S)-phenylalanine in the asymmetric aldol reaction between cyclohexanone and acetone with various aromatic aldehydes under solvent-free conditions in a ball mill has been evaluated. (S)-Proline-(S)-phenylalanine catalyzed the stereoselective formation of the expected aldol products, with higher diastereo- and enantioselectivity relative to similar reactions in solution, up to 91:9 anti:syn diastereomeric ratio and up to 95% enantiomeric excess.

Green synthesis of α,β- and β,β-dipeptides under solvent-free conditions and application in organocatalyzed asymmetric aldol reactions

244th National Meeting (2012)

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