Evans, Duffy Ripin Conformational Barriers to Rotation: Olefin A-1, 2 Interactions Chem 206 1-butene 2-propen-1-o/ 2 180 Co Deg) ΦDeg) The Torsional Energy Profile The Torsional Energy Profile Φ=50 =180H Φ=12 2.00 +133 kcal ①=0 +1.32 kcal 1.18 kcal +0.49 kcal Φ=120 +0. 37 kcal Conforms to ab initio( 3-21G)values iberg, K B; Martin, E.J. Am. Chem. Soc. 1985, 107, 50350 1 2 3 4 5 -180 -90 0 90 180 0 1 2 3 4 5 -180 -90 0 90 180 C H C H H OH H H C H C H H Me H H C C H H H Me H H Me H H C C H H H Me H H C H C H H Me H H C H C H H HO H H C C H H H OH H H C H C H H HO H H C C H H H OH H H C C H H H F F F = 0 F = 180 F = 0 F = 60 F = 120 F = 180 +1.18 kcal +0.37 kcal +2.00 kcal +1.33 kcal +1.32 kcal +0.49 kcal F = 180 F = 120 F = 50 F = 0 F = 0 F = 180 E (kcal/mol) The Torsional Energy Profile The Torsional Energy Profile Evans, Duffy, & Ripin Conformational Barriers to Rotation: Olefin A-1,2 Interactions Chem 206 (Deg) E (kcal/mol) 1-butene 2-propen-1-ol Conforms to ab initio (3-21G) values: Wiberg, K. B.; Martin, E. J. Am. Chem. Soc. 1985, 107, 5035. (Deg)