A student proposed the following synthesis.Why did it fail?
A)The use of LDA results in the thermodynamic product instead of the desired kinetic product.
B)LDA is insoluble in the THF solvent so the reaction is too slow to occur at a useful rate.
C)LDA acts as a nucleophile instead of a base in its reaction with cyclohexanone.
D)The tertiary bromide is too sterically hindered to be attacked by the enolate.
E)Instead of 2-methyl-2-bromopentane,2-bromo-3-methylpentane should have been used to anticipate a cationic rearrangement that would occur.

Question

A student proposed the following synthesis.Why did it fail? 
A)The use of LDA results in the thermodynamic product instead of the desired kinetic product. 
B)LDA is insoluble in the THF solvent so the reaction is too slow to occur at a useful rate. 
C)LDA acts as a nucleophile instead of a base in its reaction with cyclohexanone. 
D)The tertiary bromide is too sterically hindered to be attacked by the enolate. 
E)Instead of 2-methyl-2-bromopentane,2-bromo-3-methylpentane should have been used to anticipate a cationic rearrangement that would occur.

Quizplus · Accepted Answer

The tertiary bromide in the proposed synthesis is too sterically hindered to be attacked by the enolate, and thus the reaction would not proceed to give the desired product.

A Student Proposed the Following Synthesis