Chapter 17, Problem 17.29P

Interpretation Introduction

(a)

Interpretation:

The major product of the reaction is to be predicted.

Concept introduction:

Grignard reagents and alkyl lithium undergo direct addition to α,β-unsaturated carbonyls. Along with the direct addition product, they also produce a minor amount of conjugate addition product. Alkyllithium reagents generally have a greater tendency toward 1, 2-addition to $\text{α,β-}$ unsaturated carbonyls than Grignard reagents do. Alkyl lithium reagent produces less of the conjugate addition product. This greater selectivity of alkyl lithium reagents is explained by the greater concentration of negative charge on C. Thus, in the kinetically controlled addition of ${\text{R}}^{\text{-}}$ nucleophile, alkyl lithium reagents react faster with the carbonyl carbon than do Grignard reagents. The anion produced during direct addition is then protonated to obtain the final product.

Interpretation Introduction

(b)

Interpretation:

The major product of the reaction is to be predicted.

Concept introduction:

Grignard reagents and alkyl lithium undergo direct addition to α,β-unsaturated carbonyls. Along with the direct addition product, they also produce a minor amount of conjugate addition product. Alkyl lithium reagents generally have a greater tendency toward 1, 2-addition to $\text{α,β-}$ unsaturated carbonyls than Grignard reagents do. Alkyl lithium reagent produces less of the conjugate addition product. This greater selectivity of alkyl lithium reagents is explained by the greater concentration of negative charge on C. Thus, in the kinetically controlled addition of ${\text{R}}^{\text{-}}$ nucleophile, alkyl lithium reagents react faster with the carbonyl carbon than do Grignard reagents. The anion produced during direct addition is then protonated to obtain the final product.

Interpretation Introduction

(c)

Interpretation:

The major product of the reaction is to be predicted.

Concept introduction:

Grignard reagents and alkyl lithium undergo direct addition to α,β-unsaturated carbonyls. Along with the direct addition product, they also produce a minor amount of conjugate addition product. Alkyl lithium reagents generally have a greater tendency toward 1, 2-addition to $\text{α,β-}$ unsaturated carbonyls than Grignard reagents do. Alkyl lithium reagent produces less of the conjugate addition product. This greater selectivity of alkyl lithium reagents is explained by the greater concentration of negative charge on C. Thus, in the kinetically controlled addition of ${\text{R}}^{\text{-}}$ nucleophile, alkyl lithium reagents react faster with the carbonyl carbon than do Grignard reagents. The anion produced during direct addition is then protonated to obtain the final product.