Treating cis -2-propyl-3-methyl-cyclopentanone with a weak base transforms it into its trans stereoisomer. Reason this phenomenon and draw the corresponding structures.

SOLUTION:

isomerization-cis-trans-3-methyl-2-propyl-cyclopentanone

Stage 1 . Enolate formation

isomerization-cis-trans-3-methyl-2-propyl-cyclopentanone-mechanism-01

Stage 2. Protonation of the enolate on the top face to reduce repulsions between groups

isomerization-cis-trans-3-methyl-2-propyl-cyclopentanone-mechanism-02