Chapter 8, Problem 65P

Interpretation Introduction

Interpretation:The best structure for substrate A should be chosen.

  

Concept introduction:The carbonyl bond is polar with partial postive charge on carbon and partial negative charge on oxygen as illustrated below.

  

Thus it can undergo hydride addition at carbon and proton addition at oxygen. Certain reagents that are useful for such hydride addition at carbonyl carbon include ${\text{NaBH}}_{\text{4}}$ , ${\text{LiAlH}}_{\text{4}}$ .The boron and lithium in these reagents tend to push the electron of $\text{B-H}$ bond towards carbonyl carbon as illustrated below.