Key points are not available for this paper at this time.
A crush on sweetness! The coupling of a urethane-protected N-carboxyanhydride of an amino acid with another amino acid derivative under ball-milling conditions gives a protected dipeptide in very high yield (see scheme; PG: protecting group). The reaction takes place in the solid state. The synthesis was applied to the preparation of a tripeptide and the sweetener aspartame, without any organic solvent or purification.
Declerck et al. (Fri,) studied this question.