Cyclopentanones Stereochemistry of the Lithium-Liquid Ammonia Reduction of 2, 3-Dialkyl-5-Hydroxy-2-Cyclopentenones

The stereochemistry of the lithium-liquid ammonia reduction of 2, 3-dimethyl-5-hydroxy-2-cyclopentenone (1) and 3-t.butyl-2-methyl-5-hydroxy-2-cyclopentenone (2) is studied in function of a set of proton donors. A high degree of stereoselectivity is observed as practically only two (predominantly one isomer) out of the eight diastereoisomeric 3, 4-dialkyl-1, 2-cyclopentane diols 3 or 4 are formed.