Meerwein-Ponndorf - Verley determination

Kinetically controlled reaction conditions can also he employed in Meerwein-Ponndorf-Verley reductions11-78, but often appropriate control experiments to check the mechanism are lacking, for instance, determination of the ratio of stereoisomers with progressing reaction time. Low reaction temperatures, short reaction times and continuous removal of the carbonyl compound, e.g., acetone, favor kinetic reaction control. The mild conditions required for kinetic control can also be effected by a new variation of the Meerwein-Ponndorf Verley reaction11 in which three requirements are fulfilled ... 

In elegant configurational studies of biphenyls, Mislow and his associates (Newman et ah, 1958 Mislow et al., 1962) have used the Meerwein-Ponndorf-Verley reduction to determine absolute configuration. Kacemic 4, l"-dinitro-l,2,3,4-dibenz-l,3-cyclohepta-diene-6-one (DNDBCH-6-one) was partially reduced (7 hours reaction time) with S-(- -)-methyl-terf-butylcarbinol and aluminum tert-butoxide to (—)DNDBCH-6-ol. The unreacted ketone was dextrorotatory. The (+)-DNDBCH-6-one was reduced to (-1-)-... 

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