ChemInform Abstract: Remote Tricarbonyl(diene)iron Substituent Effect on Ester Heterolysis. The Solvolyses of 5,6,7,8‐Tetramethylidenebicyclo(2.2.2)oct‐2‐yl Methanesulfonate and of its Tricarbonyliron Mono‐ and Dinuclear Complexes.

Abstract

287ChemInform Abstract The mesylate (I) and the title complexes (V) ("syn-endo"), (VIII) ("syn-exo"), (Xa) ("anti-endo"), (XIIa) ("anti-exo"), (XVa) ("anti-exo,syn-endo"), and (XX) ("anti-endo,syn-exo") are derived from the corresponding alcohols using standard procedures. Their buffered acetolyses and hydrolyses are investigated. Mechanisms are given. In contrast to the solvolyses of the uncomplexed compound (I), the solvolyses of the complexes can be highly chemo-and stereoselective. The nature of the resulting products (non-rearranged bicyclo(2.2.2)oct-2-yl vs. rearranged bicyclo(3.2.1)oct-2-yl derivatives) depends on the relative configuration of the Fe(CO)3 moieties and on the medium as to be seen at the example of (XVa). The rates of solvolyses of (I) are only slightly affected by complexation, except inthe cases of the "anti-endo" complexes (Xa) and (XX) where significant rate-retardation effects (e.g. acetolysis of (Xa) ca. 500 times and hydrolysis ca. 3000 times slower than those of (I)) are observed. Buffered acetolysis (at 90 rc C) and hydrolysis (at 60 rc C) of (XX) are very slow and lead to mixtures of unidentified polyenes. Reasons for the different kinetic behaviour are discussed.