Cyclopropenimine-Catalyzed Enantioselective Mannich Reactions of tert-Butyl Glycinates with N-Boc-Imines
Jeffrey S. Bandar and Tristan H. Lambert*
*Department of Chemistry, Columbia University, New York, New York 10027, United States, Email: TL2240Columbia.edu
J. S. Bandar, T. H. Lambert, J. Am. Chem. Soc., 2013, 135, 11799-11802.
DOI: 10.1021/ja407277a (free Supporting Information)
A chiral cyclopropenimine catalyzes Mannich reactions between glycine imines and N-Boc-aldimines with high levels of enantio- and diastereocontrol. The reactivity of this catalyst is substantially greater than that of a widely used thiourea cinchona alkaloid-derived catalyst. Various aryl and aliphatic N-Boc-aldimines are effective substrates for this transformation.
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Proposed catalytic cycle