JEE Main levelOne or more correct optionsDifficulty 2 of 3o4046
Which statements about the base-induced conversion of 4-methoxybutan-2-one, CHX3COCHX2CHX2OCHX3, into but-3-en-2-one by the E1cB mechanism are correct?
AThe first step is removal of a hydrogen from C-3 to give an enolate.
BMethoxide ion is expelled from the carbanion in a later step.
CA carbocation at C-4 is an intermediate.
DThe carbon skeleton is expected to rearrange.
Answer: A, B
The base removes an acidic alpha-hydrogen at C-3 to give an enolate carbanion; in a second step, methoxide is lost from C-4. No carbocation is formed, and no skeleton change is expected.