Chapter 10: Q58P (page 540)

For each synthesis, start with bromocyclohexane and predict the products. Assume that an excess of each reactant is added so that all possible reactions that can happen will happen.

Short Answer

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Starting material

The base-catalyzed dehydrohalogenation of bromocyclohexane gives an alkene that reacts with ozone, undergoes oxidation, and reacts with m-CPBA to form the desired products.

Formation of the desired product

a) The base-catalyzed dehydrohalogenation of bromocyclohexane gives an alkene (product A). Ozonolysis of this alkene, i.e., cyclohexene in the presence of dimethyl sulfide gives a dialdehyde as the product B. Nucleophilic attack by the Grignard reagent at the aldehyde group followed by acidic workup gives the corresponding product. Thus, the overall reaction of the above reactant with given reagents in (a) is given as follows:

Formation of products in reaction a

b) The base-catalyzed dehydrohalogenation of bromocyclohexane gives an alkene as product A which undergoes oxidation in the presence of a base under thermal condition gives dicarboxylate as product E. The reduction of a diacid with lithium aluminum hydride followed by acidic workup with dilute acid gives the corresponding diol as the product F. Thus, the overall reaction of the above reactants with the given reagents in (b) is shown as follows:

Formation of products in reaction b

c) The base-catalyzed dehydrohalogenation of bromocyclohexane gives an alkene as the product A. This cyclohexene undergoes epoxidation with m-CPBA and gives the desired product. Nucleophilic attack at the epoxide by Grignard reagent followed by acidic workup with dilute acid gives alcohol as the product I. This alcohol undergoes acid-catalyzed dehydration gives more substituted alkene as the major product J. Thus, the overall reaction of the above reactant with given reagents in (c) is shown as follows: