... expected coupling pattern of H-6 endo (dd, Js-endo,7-exo - - (17) Jackman, L. M.; Sternhill, S. Applications of Nuclear Magnetic Resonance Spectroscopy in Organic Chemistry, 2nd ed.; Pergamon: London, 1969; p 289. ... 13,14-Dehydro-PGH2 Derivative J. Org. Chem., Vol. ...