The Configuration of the 2-ethylcyclohexanols
Abstract
The lactone of trans-2-hydroxycyclohexaneacetic acid (I) was prepared via reaction of sodiomalonic ester with cyclohexene oxide. Arguments for the assignment of the trans configuration to this lactone are presented. Lithium alum- inum hydride reduction of the lactone gave the trans glycol (II), 2-(2-hydroxyethyl)-cyclohexanol. Tosylation of this glycol gave the trans-di-p-toluene sulfonate (III) and the dehydration product, trans-7-oxabicyclo-(4.3.0)-nonane (IV); no monotosylation product was isolated. The trans ditosylate (III) was converted, by selective lithium aluminum hydride reduction, to trans-2-ethylcyclohexyl p-toluenesulfonate (V), the configuration of which is thus unequivocally established.The isomeric lactone of cis-2-hydroxycyclohexaneacetic acid (VI) was prepared from the trans lactone by converting the latter to the trans amide (VII), to sylating to form the pseudolactam tosylate (VIII) which has the cis ring fusion, followed by basic hydrolysis. This lactone (VI) was converted, by a similar sequence of reactions, into the cis glycol (IX), the el ditosylate (X) and the cis bicyclic ether (XI). All attempted to convert cis 2-(2-hydroxyethyl)-cyclohexyl di-p-toluene sulfonate (X) into cis-2-ethylcyclohexyl tosylate (XII) failed.The isomeric 2-ethylcyclohexanols were prepared by reduction of 2-ethylcyclohexanone. One 18omer (XIII) is formed by catalytic hydrogenation of the ketone in acetic acid; the other isomer (XIV) 18 formed by reduction of the ketone with sodium and wet ether or sodium and ethanol. The alcohols were converted into their 3,5-dinitrobenzoate by metallic reduction was converted into a 2-ethylcyclohexyl p-toluene sulfonate identical with the compound (V) prepared by a stereo specific method and is thus assigned the trans configuration. The tosylate of the alcohol (XIII) obtained by hydrogenation under acid conditions was not sufficiently esters, purified by recrystallization and regenerated by saponification of the esters. The alcohol (XIV) obtained stable to be isolated. The infrared spectra of the isomericalcohols are presented.
Degree
Ph.D.
Subject Area
Organic chemistry
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