Hydrogen exchange base-catalyzed, stereochemistry

Brown MD, Cook MJ, Hutchinson BJ, Katritsky AJ (1971) Conformational analysis of saturated heterocycles. XL. Stereochemistry of base-catalyzed hydrogen-deuterium exchange of methylene protons alpha to a sulfonyl group. Tetrahedron 27 593-600... 

The stereochemistry observed in hydrogen-exchange reactions of carbanions is very dependent on the conditions under which the anion is formed and trapped by proton transfer. The dependence on solvent, counter-ion, and base is the result of the importance of ion-pairing effects. The base-catalyzed cleavage of 1 is noteworthy. The anion of 1 cleaves at elevated temperature to 2-butanone and 2-phenyl-2-butyl anion, which under the conditions of the reaction abstracts a proton from solvent. Use of chiral 1 allows the stereochemical features of the anion to be probed by measuring the enantiomeric purity of the 2-phenylbutane product. 

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