The catalytic hydrogenation of alkenes, ketones, and imines is arguably one of the most important transformations in chemistry. Powerful asymmetric versions have been realized that require metal catalysts or the use of a stoichiometric amount of metal hydrides [Eq. (1)]. [1] Although effective and industrially relevant catalytic asymmetric hydrogenations and transfer hydrogenations of olefins and ketones have been developed, the corresponding imine reductions, although potentially highly useful for the synthesis of enantiomerically pure amines, are less advanced.[2] Living organisms employ organic dihydropyridine cofactors such as nicotinamide adenine dinucleotide (NADH) in combination with enzyme catalysts for the reduction of imines.[3] Chemical transition metal catalyzed asymmetric imine reductions have also been developed, [4] and are used, in at least one case, on an industrial scale. [5] However, with the exception of interesting Lewis base catalyzed asymmetric imine hydrosilylations, [6] organocatalytic and metal-free variants were not known. Recently, we and MacMillan and co-workers developed an asymmetric transfer hydrogenation of a,b-unsaturated aldehydes catalyzed by a chiral ammonium salt by using Hantzsch esters as a biomimetic hydrogen source. [7] Rueping et al. [8] very recently reported the development of a novel and elegant approach using Hantzsch esters as the reducing reagent for the catalytic asymmetric reduction of imines using a chiral Brønsted acid catalyst previously developed by Akiyama et al.

An overview of recent advances in the application of non‐carbonaceous nanostructured and composite materials in hydrogen storage is presented in this review. The main focus is on complex hydrides, non‐graphitic nanotubes, and other porous composite and framework materials, since carbon nanotubes have been the subject of numerous other reviews. Recent advances in the area of alanates show a promising reversible absorption capability of up to 5 %, closing in on the projected Department of Energy (DOE) target of 6 %. Non‐carbon nanotubes mainly showed a sorption capacity of 1–3 wt.‐%, although a promising level of 4.2 wt.‐% is shown by boron nitride nanotubes after collapse of their walls. Other interesting materials included here are lithium nitride and porous metallo‐organic frameworks.

A catalytic asymmetric Pictet-Spengler reaction has been developed, wherein treating substituted tryptamines with an aldehyde in the presence of a catalytic amount of a chiral phosphoric acid provides the corresponding tetrahydro-beta-carboline derivatives in high yields and enantiomeric excesses. The reaction works well with both aliphatic and aromatic aldehydes.

The selective synthesis of linear amines from internal olefins or olefin mixtures was achieved through a catalytic one-pot reaction consisting of an initial olefin isomerization followed by hydroformylation and reductive amination. Key to the success is the use of specially designed phosphine ligands in the presence of rhodium catalysts. This reaction constitutes an economically attractive and environmentally favorable synthesis of linear aliphatic amines.

[reaction: see text] The synthesis of primary amines via reductive amination of the corresponding carbonyl compounds with aqueous ammonia is achieved for the first time with soluble transition metal complexes. Up to an 86% yield and a 97% selectivity for benzylamines were obtained in the case of various benzaldehydes by using a Rh-catalyst together with water-soluble phosphine and ammonium acetate. In the case of aliphatic aldehydes, a bimetallic catalyst based on Rh/Ir gave improved results.

An in situ-generated complex from [RuCp*Cl 2 ] 2 and dpePhos ligand is reported as an efficient catalyst in the presence of 5 mol % of LiOtBu for the N-methylation of amines using methanol as the methylating agent at moderate conditions, following hydrogen borrowing strategy. This simple catalyst system provides selective N-monomethylation of substituted primary anilines and sulfonamides as well as N,Ndimethylation of primary aliphatic amines in excellent yields at 40−100°C with good tolerance to reducible functional groups. The catalytic intermediate Cp*Ru(dpePhos)H was isolated and was shown to be active for methylation in the absence of base.

A highly chemo- and regioselective hydroaminomethylation of simple as well as functionalized alpha-olefins using a cationic rhodium precatalyst together with Xantphos as ligand is reported. Studies of the influence of ligands and reaction conditions led to an unprecedented selective hydroaminomethylation procedure. The novel procedure constitutes an economically attractive and environmentally favorable synthesis of secondary and tertiary aliphatic amines.

PdCl 2 in the presence of dppe or Xantphos(t-Bu) as the ligand is found to be an efficient catalyst for the N-alkylation of various primary and cyclic secondary amines using primary alcohols at 90−130 °C under neat conditions. Interestingly, good to excellent yields were achieved when more challenging secondary alcohols were used as alkylating agents at 130−150 °C. The reaction could be easily scaled up, as demonstrated for a 10 mmol scale achieving yields up to 90% with a TON of 900.