Aluminium complexes: next-generation catalysts for selective hydroboration

Abstract

Organoboranes obtained from hydroboration reactions are one of the important classes of compounds that could be used to provide valuable synthons for follow-up transformations such as various functional group incorporation...

Mapping boron catalysis onto a phosphorus cluster platform

“…It is noteworthy that other s-and p-block catalysts have previously mediated these types of hydroborations. 1,12,43,[45][46][47] In fact, 9-BBN itself has also been employed to mediate the hydroboration of terminal alkynes and nitriles. 48,49 To probe the generality of 2 as a hydroboration catalyst, we expanded our scope to other carbon-element multiple bonds, including a ketone, alkene, alkyne, and nitrile (Table 2).…”

The transition metal-catalysed hydroboration reaction

“…Recent reviews have covered alkali and alkaline earthcatalysed hydroborations, 603 organolanthanide-and organoactinide-catalysed hydroborations, 604 and aluminum-catalysed hydroborations. 605 6.2 Reactions of B 2 (OR) 4…”

Comparing B–H Bond Activation in NiIIX(NNN)-Catalyzed Nitrile Dihydroboration (X = Anionic N-, C-, O-, S-, or P-donor)

“…Organoboron intermediates are very important in synthetic chemistry, enabling many important transformations, such as the formation of C–C , and C–N − bonds, alcohols, − imines, , and amines. − Hydroboration of unsaturated CC and CX bonds is one primary route for the production of key organoboron intermediates. − Reduction of nitriles, for example, has received much attention due to the importance of amines as precursors for the production of pharmaceutical compounds and as components of industrial processes for the production of polyesters, dyes, and agrochemicals. , The poor functional group compatibility of traditional hydroboration reagents such as diborane or alkylboranes , led to development of less reactive catecholborane (HBcat) and pinacolborane (HBpin), which do not readily reduce aldehydes at ambient temperature. , To selectively elevate the reactivity of the latter reagents, a number of first row metal and main group complexes have been employed. − Over the past decade, metal–ligand cooperation (MLC) has been shown to be particularly well-suited for catalyzed hydroboration of polar CX bonds. − In one common type of MLC, an anionic ligand X functions as a Lewis base, converting the B–H bond into a B–X bond and a metal hydride. In this type of mechanism, the formed B–X bond either has a productive role in the catalytic cycle, − known as bifunctional catalysis, or just initiates the reaction and leaves the catalytic cycle (bifunctional catalyst activation). − …”

“…23,24 The poor functional group compatibility of traditional hydroboration reagents such as diborane or alkylboranes 25,26 led to development of less reactive catecholborane (HBcat) and pinacolborane (HBpin), which do not readily reduce aldehydes at ambient temperature. 27,28 To selectively elevate the reactivity of the latter reagents, a number of first row metal and main group complexes have been employed. 29−31 Over the past decade, metal−ligand cooperation (MLC) has been shown to be particularly well-suited for catalyzed hydroboration of polar CX bonds.…”