Posts Tagged ‘Enantioselective’

Why the Sharpless epoxidation is enantioselective!

Monday, December 17th, 2012

Part one on this topic showed how a quantum mechanical model employing just one titanium centre was not successful in predicting the stereochemical outcome of the Sharpless asymmetric epoxidation. Here in part 2, I investigate whether a binuclear model might have more success. The new model is constructed using two units of Ti(OiPr)4, which are likely to assemble into a dimer such as that shown below (in this crystal structure, some of the iPr groups are perfluorinated).


Why is the Sharpless epoxidation enantioselective? Part 1: a simple model.

Sunday, December 9th, 2012

Sharpless epoxidation converts a prochiral allylic alcohol into the corresponding chiral epoxide with > 90% enantiomeric excess[cite]10.1021/jo00369a032[/cite],[cite]10.1021/jo00360a058[/cite]. Here is the first step in trying to explain how this magic is achieved.