(a)The simplest way to find the starting material is to carry out disconnection by the reverse ozonolysis and Diels-Alder reaction.

(b) The simplest way to find the starting material in (b) is to carry out disconnection by the reverse reaction of Gilman’s reagent and bromination.

(c) The simplest way to find the starting material in (c) is to carry out disconnection by the reverse reaction with Grignard reagent is shown below:

(d) The simplest way to find the starting material in (d) is to carry out disconnection by the reverse reaction with Grignard reagent is shown below:
