THE SYNTHESIS OF ARTIFICIAL SWEETENERS (PHENYLGLYCINE-ANALOGS OF ASPARTAME) IN ORDER TO EVALUATE CHANGES IN THE GAMMA-GLYCOPHORE COMPONENT-I

In order to assess the role and function of the third component (X, or gamma) in the AH, B glycophore that is a prerequisite for sweet taste , its identity and position in a series of dipeptides was studied. Fou r isomers of aspartyl-alpha-phenylglycine methyl ester 4 (isomers 4a, 4b, 4c and 4d) were synthesised and their taste reveals (1) the effect of the size of gamma; (2) the effect of the position of gamma; and (3 ) the effect of the nature of gamma. [GRAPHICS] Sensory evaluation sho wed that, as expected, only the S,S isomer, 4b, tasted sweet while the other three isomers tasted bitter. These results agree with a theory proposed by Goodman (1987). Attempts to produce the analogous S-aspart yl-N-phenylglycine methyl ester, 7, by a similar route unexpectedly yi elded a non-sweet dioxopiperazine derivative, 8, with a sour/bitter ta ste. (C) 1998 Elsevier Science Ltd. All rights reserved.