Conformational Analysis. 42. Monosubstituted Tetrahydropyrans

Abstract

The conformational energies of 2-, 3-, and 4-methyl, 2-vinyl, 2-ethinyl, 2-ethyl, 2-carbomethoxy, and 2-hydroxymethyl substituents in tetrahydropyran have been determined (in kcal/mol): 2-Me, 2.86; 3-Me, 1.43; 4-Me, 1.95; 2-CH2==CH, 2.27; 2-CH≡C, 0.34; 2-Et, 2.62; 2-CO2Me, 1.38; 2-CH2OH, 2.89. Some of these values differ appreciably from earlier reported ones, and the 2-CO2Me value does not support the hypothesis of a reverse anomeric effect. © 1982, American Chemical Society. All rights reserved.