Structure-activity relationships among 4"-(p-substituted phenylacetyl)-deltamycins, the semisynthetic macrolides.

Concerning relationships between electronegativity and antimicrobial activity, studies on chloramphenicol derivatives were reported in 19562). Antimicrobial activity of PAD derivatives (Table 1) was estimated from the relative electronegativity of the substituents in the chloramphenicol studies (Note 1) but there was no linear relationship between them. Many studies have recently shown that chemical shifts of aromatic ring hydrogen caused by substituents in NMR spectrometry correlate well with their electronegativities3) . We report in this paper that the antimicrobial activity of PAD derivatives correlates well with the electronegativity obtained from chemical shift in 1H-NMR. A series of the 1H-chemical shifts of the psubstituted phenylacetyl group in the PAD derivatives were shown in Table 2 in the order of Substituent Compd. name Compd. No.