M. N. Paddon-Row

Theoretical studies of stereoselective hydroborations

Abstract Asymmetric hydroborations of alkenes are outstanding examples of reactions which proceed with high acyclic stereoselection to give synthetically useful functionality. We have undertaken com- putational studies of these reactions as a part of our more general studies of stereoselective organic reactions. We wish to develop understanding of those factors which control stereoselectivity in known cases, and to develop both qualitative and quantitative methods to predict stereoselectivities of cases not yet investigated. Here, we detail our progress in understanding hydroborations, and in subsequent publications, we will report similar studies for other types of organic reactions, such as intermolecular and intramolecular cycloadditions, epoxidations, radical reactions, nucleophilic additions, and aldol condensations.

Synchronized distortions of bicyclobutanes

Abstract The linear relationship between flap angle, θ, and bridging bond length, r 13 , in bicyclobutanes, found empirically by Irngartinger through x-ray analysis, is reproduced by ab initio STO-3G calculations. Additional distortions of the bicyclobutane geometry which are synchronized with flap angle variations are predicted.

The magnitude of destabilization of stabilized cations by cyano and trifluoromethyl groups

Ab initio calculations predict that cyano and trifluoromethyl groups both have large destabilizing effects on α-heteroatom stabilized cations, whereas CN is a much weaker destabilizer than CF3 of less stabilized cations.