The Mannich Reaction of Malonates with Simple Imines Catalyzed by Bifunctional Cinchona Alkaloids: Enantioselective Synthesis of β-Amino Acids
作者:Jun Song、Yi Wang、Li Deng
DOI:10.1021/ja060716f
日期:2006.5.1
efficient, direct asymmetric Mannichreactions with malonates and N-Boc aryl and alkyl imines by cooperative hydrogen-bonding catalysis with a cinchona alkaloid bearing a thiourea functionality. We have also extended the scope of this reaction to beta-ketoesters. The synthetic value of this new reaction is demonstrated in the establishment of a convergent enantioselective route toward the biologically
The first asymmetric Mannich-type reaction of stabilized phosphorus ylides and N-Boc aldimines was described promoted by a readily available and recyclable chiral bisthiourea organocatalyst. Subsequent reaction with formalin smoothly provides N-Boc-β-amino-α-methylene carboxylic esters in a highlyenantiomericallyenriched form (up to 96% ee).
A chiral monophosphoric acid-catalyzed tandem aza-ene type reaction/cyclizationcascade enabled the rapid construction of enantioenriched piperidinederivatives as key structural elements of numerous natural products. The potential of such cascade transformations is highlighted through their ability to achieve a rapid increase in molecular complexity from simple enecarbamates and a broad range of aldimines
Switching Enantioface Selection in the Asymmetric Nitro-Mannich Reaction Using Single Chiral Bis(imidazolidine)pyridine–Metal Catalysts
作者:Takayoshi Arai、Eri Matsumura
DOI:10.1055/s-0034-1378204
日期:——
Switching enantioface selection of imines in the metal-catalyzed nitro-Mannich reaction was accomplished with the same enantiomer of diamine-derived bis(imidazolidine)pyridine (PyBidine) ligand. The (S,S)-PyBidine-CoCl2 complex catalyzed the nitro-Mannich reaction of N-Ts imines to give S-enriched adducts, while the Ni(OAc)(2) complex using the same ligand catalyzed the nitro-Mannich reaction of N-Boc imines in an R-stereoselective manner.
Proline-Catalyzed Mannich Reaction of Aldehydes withN-Boc-Imines