Stereochemical aspects of Michael-type additions to 5-t-butylcyclohex-2-enone
- 1 January 1972
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 2,p. 130-135
- https://doi.org/10.1039/p29720000130
Abstract
5-t-Butylcyclohex-2-enone undergoes Michael-type addition of methanol in the presence of 0·01 M-sodium methoxide at 25°. At equilibrium the mixture comprises: 5-t-butylcyclohex-2-enone (57%), trans-3-methoxy-5-t-butylcyclohexanone (28%), and cis-3-methoxy-5-t-butylcyclohexanone (15%). From a kinetic study it is found that axial attack is favoured over equatorial attack by a factor (ka/ke) of 9. The axial adduct predominates over the equatorial adduct in the equilibrium mixture by a factor of 1·9. This is discussed in the light of related examples where relatively electronegative substituents show apparently anomalous axial preferences. The base-catalysed addition of thiophenol to 5-t-butylcyclohex-2-enone has also been briefly investigated.Keywords
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