Chapter 5 - The Cyclohexane Group

Abstract

Publisher Summary This chapter discusses the preparation methods and properties of the cyclohexane group. The electrochemical reduction of benzene and some benzene derivatives can be controlled to give either nonconjugated dihydro-derivatives or tetrahydro-derivatives by the absence or presence of a cell divider in the electrolytic cell. Intramolecular reductive cyclization of diethyl deca-2,8-diene-1,10-dioate can be effected electrolytically in aqueous acetonitrile to give a high yield of diethyl cyclohexane-1,2-diacetate. Cyclization of nonconjugated alkenones to cyclohexanols may be effected electrochemically when the double bond and the carbonyl group are separated by four carbon atoms. Although cyclohexane itself on treatment with acetyl chloride and aluminium trichloride in chloroform gives 1-acetyl-2-methylcyclopentene, methylcyclohexane gives a mixture of isomeric 1-acetyl-2-methylcyclohexenes. Treatment of cyclohexanones with sodium chlorodifluoroacetate in the presence of tributylphosphine and N-methylpyrrolidine, gives a single-step synthesis of difluoromethylenecyclohexanes. The stereochemistry of some substitution reactions of trans-4-tert-butylcyclohexyl-lithium is discussed in the chapter. Carbonation, protonation, and coupling give predominantly retention of configuration, while halogenation gives some inversion.