Chapter 12.13, Problem 23ATS

Interpretation Introduction

Interpretation:

The structure of the expected product 2 and 3 for the given synthesis has to be drawn.

Concept introduction:

Lindlar reduction: The alkenes or alkynes can be reduced to alkanes with ${\text{H}}_{\text{2}}$ in the presence of metal catalyst $\left(\text{Pd}\right)$.  This heterogeneous catalyst that consists of palladium deposited on calcium carbonate which is then poisoned with various forms of lead or Sulphur.  The new $\text{C-H σ}$ bonds are formed simultaneously from $\text{H}$ atoms absorbed into the metal surface.

Benzyl bromide acts as protecting reagent which is used to protect hydroxyl group.

Reducing agent: Aldehydes or ketones undergoing reduction by using reducing agent like ${\text{LAH or LiBH}}_{\text{4}}$ which provides alcohol.

Sodium hydride is a strong base that used to remove the hydroxyl protons.

Partial hydrogenation: Metal like palladium on calcium carbonate that's been doped with lead.  It's used for the hydrogenation of alkynes to alkenes, not for complete reduction like alkyne to alkane.