The configurations and P.M.R. spectra of iodo lactones and oxymercurials derived from some 5-Norbornene-2-endo-carboxylic acids

Abstract

Iodo lactones and chloromercuri lactones derived from a number of 2- and 3-methyl-5-norbornene-2-endo-carboxylic acids have been prepared and characterized. Analyses of 60-MHz and 100-MHz proton magnetic resonance spectra have estab- lished their configurations, which conform to a general pattern of trans-addition. Criteria for stereochemical assignments in this system can be based upon identifiable vicinal, geminal, and some long-range 1H-1H and 1H-199Hg coupling constants. These criteria are used to establish that 5-norbornene-2-endo,3-endo-dicarboxylic acid and its derivatives do not follow the cis-oxymercuration route previously suggested.