Chapter 11, Problem 11.29P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for the addition of $\text{HCl}$ to dihydropyran is to be drawn, and the major product is to be predicted.

Concept introduction:

The electrophilic addition of ${\text{H}}^{\text{+}}$ to the C=C double bond produces carbocation intermediate. The more stable carbocation proceeds to the next coordination step. In the next step, the nucleophile attacks the positively charged ${\text{C}}^{\text{+}}$ carbon atom to form a neutral product.

The carbocation intermediate is a trigonal planar, and the nucleophile can attack the ${\text{C}}^{\text{+}}$ from the front (wedge) or from behind (dash). This leads to two different products.