When solving these problems you first look at the circled target products and then do a retrosynthesis on paper to figure out what starting reactant and reagent will either in one step lead to the target product or in one step will lead to an intermediate that can then lead to the target product

Reactants Reagents Target Product HC 1. Mix Reactants in DMSO or THF (solvent) (2. H2O (Aqueous workup)) CH, . CH, Reaction Explorer New HC Problem CHE Printer Friendly click on a reactant to add it to the synthesis pathway NaNH2 Solution Br-CH3 Review Examples Alkynes (0.138 sec) Link Reload Reactants Reload Reagents Reload Pathway / Workspace CH. Pathway (0.000 sec) Reactants Reagents Products Select a Reagent Select a Reactant Apply Reaction to Generate Product(s)