Celestolide, a perfuming agent with a musk odor, is prepared by the sequence of reactions given in Fig. P16.52.

(a) Give the curved-arrow mechanism for the formation of compound A (reaction a).

Fig. P16.52

(b) In your mechanism, identify the three basic steps of electrophilic aromatic substitution discussed in Sec. 16.48.
(c) What product would be obtained in reaction b if this reaction followed the usual directing effects of alkyl substituents? Suggest a reason that celestolide is formed instead.

(CH), HSO CH,CH CCH, CH H,C CH HC CH 2) Hd (L.i equv(CH,),C 2) HO ) HC-C (CH C CH3 celestolide