Chapter 15, Problem 25P

Interpretation Introduction

Interpretation:

The configuration of $2-\text{phenylbutane}$ produced by the reaction of lithium diphenylcuprate with optically active $\text{2-bromobutane}$ is to be determined.

Concept introduction:

With net inversion of configuration, lithium dialkylcuprates react with alkyl halides.

A new carbon-carbon bond is formed between the alkyl group of the halide and the cuprate.

The Cahn-Ingold-Prelog rule system ranks the substituents in the chirality center in the order of decreasing atomic number.

After the substituents at the chiral center is ranked with decreasing priority order, the next step is to orient the molecule so that the bond to the lowest ranked substituent points away from the observer. This is used to determine if the sequence of decreasing priority of the other three substituents is clockwise or counterclockwise. If this path is clockwise, then the configuration is $R$, and if it is counterclockwise, the configuration is $S$.