Efficient and Selective Iron-Complex-Catalyzed Hydroboration of Aldehydes

Abstract

An imine-coupled [Fe–N2S2]2 complex, prepared from a readily available benzothiazolidine ligand, catalyzes selectively the hydroboration of aliphatic and aromatic aldehydes at low catalyst loadings (0.1 mol %) using pinacolborane. Both mono- and disubstituted aromatic and aliphatic aldehydes are hydroborated selectively in the presence of ketones, nitriles, alkenes, amines, and halides. Reaction of the [Fe–N2S2]2 complex with CO and preliminary reaction progress kinetic studies point to a complex mechanism.

Hydroboration of aldehydes, ketones and CO2 under mild conditions mediated by iron(iii) salen complexes

“…5200 easily achieved in one instance. 26 In addition, the first case of an iron(II) coordination polymer and heterogenous Fe 2 O 3 nanoparticles mediated hydroboration of these carbonyl moieties have been reported by Zhang and co-workers 27,28 and Geetharani, Bose and coworkers 29 respectively. A more difficult but highly desired transformation is the asymmetric hydroboration of ketones to achieve optically active secondary alcohols, 1 with only a handful of examples using iron complexes reported to date.…”

Emergence and Applications of Base Metals (Fe, Co, and Ni) in Hydroboration and Hydrosilylation

“…Following these initial reports, many other studies employing iron-based catalysts for similar transformations have now subsequently appeared in the literature (Scheme 1). Baker and co-workers reported an imine coupled [Fe-N 2 S 2 ] 2 complex ( 5 ), which was found to be highly efficient in hydroboration of aldehydes at a catalyst loading of 0.1 mol% [53]. This catalyst was found to preferentially promote hydroboration of aldehydes over ketones; it was also found to be selective for the aldehyde moiety in intramolecular hydroboration of 4-acetylbenzaldehyde.…”

“…Similarly, Geetharani and co-workers observed a peak at 1658 cm −1 upon stoichiometric addition of ( 7 ) and HBPin; substituting HBPin to DBPin showed a shift in the peak to 1204 cm −1 , suggesting the formation of a Fe-D species [55]. A detailed kinetic study by Baker and co-workers further revealed that the role of HBPin could be in the activation of the iron pre-catalyst ( 5 ) as the rate of consumption of HBPin was greater than that of aldehydes [53]. All these studies insinuate the generation of Fe-H intermediate species, and this might be the key step in the hydroboration of aldehydes and ketones.…”

Ultrafast Iron‐Catalyzed Reduction of Functionalized Ketones: Highly Enantioselective Synthesis of Halohydrines, Oxaheterocycles, and Aminoalcohols

“…[9][10][11] This development has been the focus of many recent studies in which the potential of 3d metals in enantioselective catalysis for the reduction of carbon-carbon and carbonheteroatom multiple bonds has been reported. [9][10][11] This development has been the focus of many recent studies in which the potential of 3d metals in enantioselective catalysis for the reduction of carbon-carbon and carbonheteroatom multiple bonds has been reported.…”

“…In this context, the development of novel catalytic systems based on environmentally benign and earth-abundant base metals still provides ac hallenge in this field of research. [9][10][11] This development has been the focus of many recent studies in which the potential of 3d metals in enantioselective catalysis for the reduction of carbon-carbon and carbonheteroatom multiple bonds has been reported. [12] Them ajority of these studies is limited to simple diaryl, aryl alkyl, and dialkyl ketones as the substrates,w ith more complex structures being explored only in selected cases.…”