Factors which affect the direction of the reaction of nucleophilic addition of CH2XCO2Et to?,?-unsaturated aldehydes in conditions of two-phase catalysis

Abstract

1. The general mechanisms of the direction of addition of CH acids of the XCH2CO2Et and BrCH(CO2Et)2 type to enals in conditions of two-phase catalysis were formulated: a) CH acids (X=CO2Et, COCH3, CN) are added to enals unsubstituted in position 3 only at the C=C bond; b) enals monosubstituted in position 3 add CH acids (X=CO2Et, COCH3) at the C=C bond and CH acids (X=CN) at the C=O bond; c) enals disubstituted at position 3 add CH acids (X=CO2Et, COCH3, CN) exclusively at the C=O bond. 2. Quantum-chemical calculations showed that the direction of the reaction of addition of CH acids to enals cannot be explained based on concepts concerning the competition of orbital and charge interactions. 3. The change in the direction of addition in methylation and chlorination of the enal is due to steric hindrances which arise when the structure of the enal is altered when the reagents converge.