Since Betancort and Barbas reported the first organocatalytic asymmetric Michael addition of aldehydes to nitroalkenes, [1] a great effort has been devoted to the development of more selective and efficient catalytic systems for this synthetically useful transformation, [2][3][4] and significant progress has been made. Especially, the use of o-TMS-protected diphenylprolinol (1; TMS = trimethylsilyl) [3e] or pyrrolidine sulfonamide (2) [3d,h] as catalysts has given rise to excellent enantioselectivities in the reactions. However, for a long time, these reactions required a large excess of donor source (up to 10 equivalents of aldehyde) as well as high catalyst loadings (between 10 and 20 mol %), and they gave poor results when alkyl-substituted nitroalkenes were employed. These problems were efficiently solved by Palomo and co-workers by using the newly designed catalyst 3.[3j] However, a loading of more than 5 mol % of this catalyst was still required in their experiments (although, at the time, this represented the lowest catalyst/substrate ratio employed in any enamine-based Michael addition with excellent enantioselectivity). While catalyst design has been the subject of several studies, little attention has been paid to exploring functionalized nitroalkene compounds as substrates.[3b,n] Such studies would be of immense benefit for expanding the scope of application of this reaction in organic synthesis. We recently found that b-nitroacrylate compounds are suitable acceptors for this reaction, the products of which are the precursors of biologically important b-amino acids [5] and b-lactams.[6] Accompanying this study, a more efficient catalytic system (which works in water and requires only 0.5-2 mol % of catalyst for the known substrates) was discovered. Herein, we disclose our results.The required b-nitroacrylate compounds were easily accessible by the condensation of glyoxylic acid with nitromethane and subsequent esterification and elimination. Initially, we conducted our Michael addition under the conditions reported by Hayashi et al. [3e] We found that after 24 h, the desired adduct 5 and its epimer were produced with good diastereoselectivity and enantioselectivity (entry 1, Table 1). However, the conversion was incomplete, which prompted us to vary the reaction conditions. Changing the solvent to toluene led to a faster reaction, but the diastereoselectivity decreased significantly (entry 2, Table 1). Barbas and co-workers recently reported that water and brine were good media for organocatalytic reactions. [3k, 7a] We were pleased to see that our reaction worked well in water to afford compound 5 with a high enantioselectivity (97 % ee) and good diastereoselectivity (entry 3, Table 1). Since it had been observed that the addition of some Brønsted acids could promote the formation of enamines, thereby accelerating amine-catalyzed reactions, [3a, 8] we conducted the reaction in the presence of benzoic acid. When benzoic acid (100 mol %) was added, the reaction was greatly accelerated, although poo...

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