Alicyclic Diketones and Diols

Allan, Angus W (1959) Alicyclic Diketones and Diols. PhD thesis, University of Glasgow.

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cis- and trans-2:2:5:5-Tetramethylcyclohexane-1:3-diol were prepared from 5:5-dimethyIcyclohexane-1 :3-dione (dimedone) and, contrary to previous findings, the low-melting diol was shown to he the trans-isomer by resolution through the bis-(-)-menthoxyacetates. The cis-diol was shown, by infrared methods, to have the diequatorial conformation. Dehydration of both cis- and trans-2:2:5:5-tetra-methylcyclohexane-1:3-diol with potassium bisulphate gave l:l-dimethyl-4-isopropylidenecyclopent-2-ene , 2:3:5:5-tetramethylcyclohexanone and 2:2:5:5-tetramethylcyclohex-3-enol. The diene was hydrogenated to 1:1-dimethyl-3-isopropylcyclopentane which was synthesised from (+)-fenchone. 2:3:5:5-Tetramethylcyclohex-2-enone and 2:2:5:5-tetramethyl-cyclohexanol were both synthesised from dimedone and correlated with the saturated ketone and unsaturated alcohol respectively from the dehydrations of the diols. Mechanisms were put forward for the dehydrations. In an attempt to synthesise a-pinene, 4-methoxy-carbonyl-5:5-dimethylcyelohexane-l:3-dione (Vorlander's ester) was prepared and the structure of its enol ether elucidated. Lithium aluminium hydride reduction of the enol chloride of Vorlander's ester gave 3-chloro-5:5-dimethyl-6-hydroxymethylcyclohex-2-enol. Dieckmann cyclisation of 1:6-diethoxycarbonylhexan-2-one, synthesised from ethyl hydrogen adipate, gave not the anticipated cycloheptane-1:3-dione, but 2-(carboethoxyacetyl)-cyclopentanone and a further cyclisation product, 4-hydroxy-5:6-trimethylene-2-pyrone. The former was converted to 2-(carbobenzyloxyacetyl)-cyclopentanone and hence to 2-acetyl-cyclopentanone which was also obtained by hydrolysis of the pyrone. The ultra-violet spectra of several acylcyclanones, B-keto-esters and their copper enolates were studied.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Organic chemistry
Date of Award: 1959
Depositing User: Enlighten Team
Unique ID: glathesis:1959-79328
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 10:43
Last Modified: 05 Mar 2020 10:43

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