Mukaiyama–Michael Reactions with trans‐2, 5‐Diarylpyrrolidine Catalysts: Enantioselectivity Arises from Attractive Noncovalent Interactions, Not from Steric Hindrance. Issue 20 (1st April 2014)

• Record Type: Journal Article
• Authors: Kemppainen, Eeva K.; Sahoo, Gokarneswar; Piisola, Antti; Hamza, Andrea; Kótai, Bianka; Pápai, Imre; Pihko, Petri M.
• Is Part Of: Chemistry. Volume 20:Issue 20(2014)
• Page Start: 5983
• Page End: 5993
• Publication Date: 2014-04-01
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201304240
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The scope of the enantioselective Mukaiyama–Michael reactions catalyzed by <italic>trans‐</italic>2, 5‐diphenylpyrrolidine has been expanded to include both α‐ and β‐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 CC 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.</p> </abstract>