REDUCTION WITH METAL HYDRIDES. VIII. REDUCTIONS OF KETONES AND EPIMERIZATION OF ALCOHOLS WITH LITHIUM ALUMINUM HYDRIDE-ALUMINUM CHLORIDE
Whereas lithium aluminum hydride (LAH) reduced 4-tbutylcyclohexanone to a mixture of 90% trans-4-t-butylcyclohexanol and 10% cis-4-t-butylcyclohexanol, LAHAlCl/sub 3/ (1: 4 ratio) yields 80% trans- and 20% cis-alcohol under kinetically controlled conditions. Addition of excess ketone or acetone at the end of the reaction leads to thermodynamic control of the reaction products with conversion of the alcohol mixture to one containing over 99% of the trans isomer in less than fifteen minutes. The fast reaction and overwhelming preponderance of the trans isomer is ascribed to the nature of the species equilibrated which are bulky aluminum complexes, not readily accommodated in the axial position of the cyclohexane ring. The equilibration procedure was utilized to determine the conformational equilibrium values for methyl and phenyl groups. The conformational free energy differences are 1.5 plus or minus 0.1 kcal/mole for methyl and ca. 2.6 kcal/mole for phenyl. (auth)
- Research Organization:
- Univ. of Notre Dame, Ind.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-14-014737
- OSTI ID:
- 4140604
- Journal Information:
- Journal of the American Chemical Society (U.S.), Journal Name: Journal of the American Chemical Society (U.S.) Vol. Vol: 82; ISSN JACSA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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