Using benzene and any necessary organic or inorganic reagents, suggest efficient syntheses...

Using benzene and any necessary organic or inorganic reagents, suggest efficient syntheses of

(a) Isobutylbenzene, C6H5CH2CH(CH3)2

(b) (2,2-Dimethylpropyl)benzene, C6H5CH2C(CH3)3

Sample Solution (a) Friedel-Crafts alkylation of benzene with isobutyl chloride is not suitable, because it yields tert-butylbenzene by rearrangement.

The two-step acylation-reduction sequence is required. Acylation of benzene puts the side chain on the ring with the correct carbon skeleton. Clemmensen reduction converts the carbonyl group to a methylene group.