Chapter 19, Problem 19.68P

Interpretation Introduction

Interpretation:

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

Concept introduction:

In a hydroboration–oxidation reaction, $\text{H and OH}$ adds to an alkene in a syn fashion, with anti-Markovnikov regiochemistry, to produce an alcohol. In an anti-Markovnikov’s addition, the hydroxyl group adds to the doubly bonded carbon atom having less number of hydrogen attached.

Pyridinium chlorochromate (PCC) is a partial oxidizing agent. Oxidation of a primary alcohol by pyridinium chlorochromate (PCC) stops at the aldehyde because the reaction takes place in a nonaqueous medium. Pyridinium chlorochromate (PCC) oxidizes a primary alcohol to an aldehyde and a secondary alcohol to a ketone.

A Wittig reagent, also called a phosphonium ylide, is characterized by a ${\text{P}}^{+}{\text{- :C}}^{-}$ bond and is strongly nucleophilic at the negatively charged carbon atom. In a Wittig reaction, the phosphonium ylide undergoes nucleophilic addition to the $\text{C=O}$ bond of a ketone or aldehyde and, after subsequent elimination, results in the formation of an alkene.

Oxymercuration–reduction proceeds through a mercurinium ion intermediate and results in the addition of water to an alkene or alkyne with Markovnikov regiochemistry.

When treated with a basic solution of potassium permanganate (${\text{KMnO}}_4$), followed by aqueous acid: Primary alcohols and aldehydes are converted to carboxylic acids, while secondary alcohols are converted to ketones. However, tertiary alcohols do not undergo an oxidation reaction with ${\text{KMnO}}_4$.

LDA is a strong base and is used to deprotonate the least substituted carbon atom in the ketone. The alkylation at this alpha carbon takes place via the conjugate addition of alkyl bromide.