Remarkable orientational effects in the displacement of the fluorine from heptafluoro-isoquinoline and -quinoline towards sulfur nucleophiles. Further reactions with oxygen nucleophiles

Abstract

Heptafluoroisoquinoline 1 and heptafluoroquinoline 2 have been treated with a variety of sulfur and oxygen nucleophiles and some reactivities have been measured relative to treatment with ethoxide. The significant feature is that the major sites of attack by the sulfur and the oxygen nucleophiles are significantly different: attack occurs at the 6-position by sulfur and the 1-position by oxygen nucleophiles in the isoquinoline derivative 1 irrespective of the relative reactivities; and at the 4-position by sulfur and at both the 2- and 4-positions by oxygen nucleophiles in the quinoline derivative 2. The results have been rationalised on the basis of the relative hardness/softness of the nucleophiles and the known activating influences of the fluorine atoms at sites remote from the reaction centre.