Chapter 19, Problem 19.69P

Interpretation Introduction

Interpretation:

The missing intermediates and final product for the given synthesis are to be provided.

Concept introduction:

Alkene on treatment with molecular bromine, the addition of bromine across the double bond takes place in a trans passion. When dibromo alkane ($\text{1, 1-dibromo or 1, 2-dibromo}$) heated under the strong basic condition the double elimination takes place to form the corresponding alkyne. Alkyne on catalytic hydrogenation (e.g. Lindlar catalyst) always forms cis product. The proton of the terminal alkyne is acidic and abstracted by the strong base, the corresponding carbanion is formed which reacts with alkyl halide through SN2 mechanism and replaces bromine atom. Alkene on treatment with peracid an epoxide is formed by the addition of oxygen across the double bond. An epoxide when heated with Grignard reagent the ring is opened and nucleophile adds to the less sterically hindered carbon of the ring which on acid workup corresponding alcohol is formed. Secondary alcohol on treatment with chromic acid (${\text{H}}_{\text{2}}{\text{CrO}}_{\text{4}}$) an oxidizing agent corresponding ketone is formed.