Part I. Conformational effects on the proton magnetic resonance spectra of six-membered ring compounds. Part II. A study of the effect of a 3-methoxy group on the stereochemical routes and the reactivities of a variety of 1,2-substituted cyclohexanes

Part one. The NMR spectra of six-membered ring compounds show an approximately three times larger spin coupling constant for 1,2-diaxial hydrogen atoms than for 1,2-hydrogen atoms in other conformational relationship. Signals for equatorial hydrogen atoms are generally found at lower fields than those for the corresponding axial hydrogen atoms. The signals of equatorial acetoxy or methoxy groups, however, are usually observed at higher fields than their axial equivalent. The observations are applied to several determinations of configuration and conformation with emphasis on the acetylated aldopyranoses and some theoretical implications of the results are discussed. Part two. It was found possible to assign the structures and configurations to two of the diastereoisomeric 1,3-dimethoxy-2-acetoxycyclohexanes on the basis of their NMR spectra and thereby assign configurations to the parent diastereoisomeric 3-methoxycyclohexene oxides. The conclusions thus reached were substantiated by chemical means. Two new isomeric 3-methoxy-1,2-cyclohexanediols were isolated and their structures were established. The rates of the periodate oxidation of these compounds and of the other two previously known isomers were examined. Furthermore, the relative electrophoretic mobilities of the four isomers, on borate buffered filter paper, were determined. The structures and configurations of the epimeric 3-methoxy derivatives of trans-1-tosyloxy-2-acetoxycyclohexane were established and the rates of their acetolyses measured. The results of the rate studies and electrophoretic migration measurements are discussed in terms of interactions between the 3-methoxy groups and the 1,2-cyclic ions formed as reaction intermediates.