Reinvestigation of the reaction between 2-methylsulphonylcyclohexanone and morpholine: long-range effect of a chiral centre on the chemical shift equivalence of morpholine protons

Abstract

The reaction between 2-methylsulphonylcyclohexanone (1a) and morpholine leads only to 3-methylsulphonyl-2-morpholinocyclohexene (2a),†; and not to a mixture with the 1-methylsulphonyl isomer (3) as reported previously. A complexity in the 1H n.m.r. spectrum is explained by the distant chiral centre at C-3, which renders the geminal methylene protons α to nitrogen diastereotopic.