David J. Phelps

The lack of allylic oxidation in the moffatt oxidation. Preparation of 5α-lanost-8-en-3-one.

Abstract The Moffatt oxidation (dimethyl sulfoxide-dicyclohexylcarbodiimide) is successful in oxidizing 5α-lanost-8-en-3β-01 (I) to 5α-lanost-8-en-3-one (II) without any detectable trace of the usual competing allylic oxidation products.

The influence of remote substituents on amide bond formation. The reaction of oxazolinones with benzylamine

The second-order rate constants for the reaction of nine substituted (Z)-4-benzylidene-2-phenyloxazolin-5-ones with benzylamine in acetonitrile have been obtained. There is an electronic effect in the predicted direction for substitution in either ring. There is a difference in steric effects which appears to be ring specific. ortho-Substituents in the benzylidene ring lead to rate enhancement while ortho-substituents in the phenyl ring retard the rate. The reaction of the oxazolinones with α-methylbenzylamine indicates a large steric effect upon increasing steric demand in the nucleophile.

The validity of the spectrophotometric method for determination of the kinetics of the reduction of ketones with sodium borohydride

The kinetics of reduction of a number of ketones by sodium borohydride have been followed spectroscopically and give good second-order plots with correlation coefficients ca. 0·999 and essentially zero intercepts at zero time. These plots yield satisfactorily reproducible rate constants over a range of concentrations. The results suggest that the spectral method is satisfactory for measurement of these kinetics. The values of the rate constants are in agreement with those previously obtained by potentiometric and chromatographic methods but considerably higher than those obtained by the iodate titration method.

Transition state analysis: evidence against product development control in the sodium borohydride reduction of ketones

The kinetic isotope effects in the reduction of ketones of varying degrees of steric hindrance by NaBH4 and NaBD4 are small, inverse, and essentially independent of the amount of steric hindrance, a result in direct conflict with the steric-approach-control–product-development-control explanation of the axial: equatorial alcohol product ratios observed.