The Henry (nitro aldol) reaction, 1 and its aza analogue, 2 are fundamental C-C bond-forming reactions in organic chemistry. Compared with the development of catalytic enantioselective aldol reactions, there are astonishingly few examples on asymmetric catalytic nitro aldol reactions. Only the chiral heterobimetallic catalysts reported by Shibasaki et al. have proven to be effective for asymmetric Henry reactions. 3 In extension of this work, they have developed a catalytic asymmetric aza-Henry reaction (nitro-Mannich reaction). 3c When nitromethane was used as the substrate, high enantioselectivities were obtained for this reaction using N-phosphinoylimines. However, 60 mol % of the chiral ligand in the chiral ytterbium catalyst was required, and successful reactions were reported for only nitromethane.This communication presents the first catalytic highly diastereoand enantioselective aza-Henry reaction that proceeds in the absence of a base and with lower catalyst loading. In this reaction, the presence of a base is avoided by the application of silyl nitronates 1a-d instead of nitro compounds for the reaction with R-imino esters 2a-c in the presence of a chiral Lewis acid. It should be noted that a racemic fluoride-induced reaction of silyl nitronates with aldehydes has been described by Seebach et al., 4 and very recently another racemic version of this reaction using Sc(OTf) 3 was reported. 5

Imines have been reduced to amines in high yield, and with excellent chemoselectivity, by catalytic hydrogenation in a continuous flow-reactor, utilising an electrochemically-generated hydrogen source to produce a mixed hydrogen-liquid flow stream.

5-Pyrrolidin-2-yltetrazole performs as a useful organocatalyst for the asymmetric addition of malonates to a range of enones, with good to excellent enantioselectivities.

An approach to asymmetric catalysis based on chiral molecular recognition by the combination of chiral Lewis acids and chiral organocatalysis for the formation of optically active quarternary centers in the aza-Henry reaction is presented; this procedure leads to products with up to 98% ee and a diastereomeric ratio of 14 : 1 in excellent yields with catalyst loadings of 5 mol%.