Mukaiyama-Michael Reactions with trans-2,5-Diarylpyrrolidine Catalysts: Enantioselectivity Arises from Attractive Noncovalent Interactions, Not from Steric Hindrance

作者：Kemppainen Eeva K; Sahoo Gokarneswar; Piisola Antti; Hamza Andrea; Kotai Bianka; Papai Imre^*; Pihko Petri M

来源：Chemistry - A European Journal, 2014, 20(20): 5983-5993.

DOI：10.1002/chem.201304240

• DFT calculations
• enantioselectivity
• noncovalent interactions
• organocatalysis
• transition states

The scope of the enantioselective Mukaiyama-Michael reactions catalyzed by trans-2,5-diphenylpyrrolidine has been expanded to include both - and -substituted enals. However, the rationalization of the observed enantioselectivity is far from obvious since the catalyst is not very sterically hindered. DFT calculations were carried out to rationalize the observed stereoselectivities. Transition states of the CC bond formation between iminium intermediates and silyloxyfurans were located and their relative energies were used to estimate the stereoselectivity data. We find excellent agreement between the predicted and observed stereoselectivities. The analysis of intermolecular forces reveals that the enantioselectivity is mostly due to stabilizing noncovalent interactions between the reacting partners, not due to steric hindrance. The role of attractive noncovalent interactions in enantioselective catalysis may be underappreciated.

• 出版日期2014-5-12