The origin of enantioselectivity in the l-threonine-derived phosphine-sulfonamide catalyzed aza-Morita-Baylis-Hillman reaction: Effects of the intramolecular hydrogen bonding

Abstract
l-Threonine-derived phosphine-sulfonamide 4 was identified as the most efficient catalyst to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions, affording the desired aza-MBH adducts with excellent enantioselectivities. Density functional theory (DFT) studies were carried out to elucidate the origin of the observed enantioselectivity. The importance of the intramolecular N-H⋯O hydrogen-bonding interaction between the sulfonamide and enolate groups was identified to be crucial in inducing a high degree of stereochemical control in both the enolate addition to imine and the subsequent proton transfer step, affording aza-MBH reactions with excellent enantioselectivity. © 2013 The Royal Society of Chemistry.

Citation
Lee, R., Zhong, F., Zheng, B., Meng, Y., Lu, Y., & Huang, K.-W. (2013). The origin of enantioselectivity in the l-threonine-derived phosphine–sulfonamide catalyzed aza-Morita–Baylis–Hillman reaction: effects of the intramolecular hydrogen bonding. Organic & Biomolecular Chemistry, 11(29), 4818. doi:10.1039/c3ob40144h

Acknowledgements
We are grateful for the generous financial support from King Abdullah University of Science and Technology to K.-W.H. and from the National University of Singapore and the Ministry of Education (MOE) of Singapore (R-143-000-494-112) to Y. L.

Publisher
Royal Society of Chemistry (RSC)

Journal
Organic & Biomolecular Chemistry

DOI
10.1039/c3ob40144h

PubMed ID
23774825

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