“…The differences in taste potencies between 4 (400X), 6 (210X), 7 (Ox), and 8 (70X) were quite unanticipated. We (DuBois et al, 1981) and others (Esaki et al, 1975;Kamiya et al, 1976Kamiya et al, ,1978 have prepared a large number of potently sweet NHDHC analogues with quite diverse C-4 functionality. Why then are such great differences in potency observed for the above amino acids which appear to have very similar C-4 substituents?…”