Asymmetric synthesis. Part VI. Reactions of 3,3,5-trimethylcyclohexanone with Grignard reagents and configurational interrelationships of 1-alkyl(alkenyl and alkynyl)-3,3,5-trimethylcyclohexanols and compounds derived from 1-hydroxy-3,3,5-trimethylcyclohexanecarbonitriles
Abstract
The reactions of 3,3,5-trimethylcyclohexanone (I) with methyl-, ethyl-, vinyl-, allyl-, prop-2-ynyl-, isopropyl-, and t-butyl-magnesium halides and with methyl-, ethyl-, isopropyl-, and t-butyl-lithium gave one product in each case. Chemical correlations and n.m.r. data showed that all had the same relative configuration (trans-1 -OH,5-Me). The epimeric cyanohydrins from 3,3,5-trimethylcyclohexanone provided a route to the epimeric methyl 1-hydroxy-3,3,5-trimethylcyclohexanecarboxylates; configurational interrelationships with the 1-alkyl analogues are reported. Contrary to a previous report, reactions of the ketone (I) with both dimethyloxosulphonium methylide and dimethylsulphonium methylide gave the same oxiran, which on reduction gave the trans-compound. Epoxidation of 1,1,3-trimethyl-5-methylenecyclohexane and reduction of the resulting oxiran gave the elusive 1,3,3-cis-5-tetramethylcyciohexanol, the configuration being supported by n.m.r. data for the oxiran precursor.
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