Hydroboration of Alkenes and Alkynes Employing Earth‐Abundant Metal Catalysts

Abstract

Iron complexes [BIAN]Fe(I)(η6‐toluene) (M1) and [BIAN]FeCl2 (M2) (BIAN=bis(2,6‐diisopropylaniline)acenaphthene) were found to be viable catalysts for the regioselective hydroboration of alkynes and alkenes. The hydroboration of alkynes and alkenes in the presence of HBpin and an activator at 70 °C afforded linear vinyl and alkyl boronic esters, respectively. Selectivity up to 98% was observed for alkyl boronic esters and exclusive formation of trans product was observed for vinyl boronic esters.

Iron-catalysed hydroboration of non-activated imines and nitriles: kinetic and mechanistic studies

“…The low abundance, high cost and toxicity of precious metal elements has prompted the catalytic community to focus heavily on an examination of the use of base metals in catalysis. 43 Our group has a long standing interest in employing earth abundant metal catalysts in a variety of transformations such as aldehyde and ketone hydrosilylation, 44 imine hydrosilylation, 11 alkene and alkyne hydroboration, 45 ester and amide reduction. 46,47 Iron has emerged as a leading candidate in 1st-row metal catalysis as it is the most abundant transition metal and the fourth most abundant element in the Earth's crust, it is environmentally benign, cost effective and has long-term commercial availability.…”

Redox‐active BIAN‐based Diimine Ligands in Metal‐Catalyzed Small Molecule Syntheses**

“…[69,70] The three-component synthesis of Scheme 11. Fe(BIAN)-catalyzed hydrofunctionalizations: i) Hydrosilylation of aldehydes, ketones, imines; [57,60] ii) hydroboration of alkynes, alkenes; [62] iii) hydroboration of ketones. [63] Scheme 12.…”

Activation Strategies for Earth-Abundant Metal Catalysis

“…24 Moreover, this activation protocol was applied to a number of Earth-Abundant metal-catalysed industrially relevant transformations. 25 4. 'Activator-Free' Systems 'Activator-free' hydrofunctionalisation systems have recently been reported, in which Earth-abundant metal pre-catalysts undergo activation without the need for external activators.…”