Hydroaminations of Alkenes: A Radical, Revised, and Expanded Version

Abstract

Radical changes: The applicability of alkene hydroamination has recently been significantly expanded by the development of radical variants that are based on initial hydrogen atom transfer to the alkene. This Highlight assesses the current state of the art, focusing on an iron-catalyzed reaction that utilizes stable nitroarenes as the electrophilic N component and is based on the dual catalytic activation of both starting materials.

First-Row Late Transition Metals for Catalytic Alkene Hydrofunctionalisation: Recent Advances in C-N, C-O and C-P Bond Formation

“…In this process, iron-hydride species (generated in situ from iron(III) acetylacetonate and phenysilane) mediate the formal single-electron reduction of both partners, the nitro(hetero)arene and the olefin into, respectively, a nitroso(hetero)arene and an alkyl radical. Subsequent radical attack of one equivalent of the alkyl radical (generated from the olefin) on the nitroso(hetero)arene furnishes a O-centred radical species which is further reduced to provide the formal hydroamination product [ 23 , 35 ]. One year later, the groups of Shenvi [ 36 ] and Thomas and Shaver [ 37 , 38 ] brought some modifications to the initial conditions developed by Baran and co-workers by using isopropoxy(phenyl)silane (instead of phenylsilane) and an amine–bis(phenolate)iron(III) complex (instead of iron(III) acetylacetonate), respectively.…”

Markovnikov-Selective, Activator-Free Iron-Catalyzed Vinylarene Hydroboration

“…The regioselectivity of the Markovnikov selective hydroboration of styrene derivatives with HBpin and alkoxy-tethered complex 2a can be rationalized by the formation a stabilized benzyl-iron intermediate following hydrometallation. For the anti-Markovnikov selective hydroboration reactions with the more electrophilic HBcat, where catalyst decomposition is observed, a Lewis acid/base promoted, 40 or radical hydrogen-atom transfer 41 reactions cannot be ruled out. However, we also cannot exclude the formation of a kinetically favored terminal alkyl-iron intermediate when using HBcat.…”

Amine synthesis via iron-catalysed reductive coupling of nitroarenes with alkyl halides

“…1d ). Nevertheless, this approach was mostly efficient for the synthesis of (hetero)aryl amines substituted by a tertiary alkyl group 15 . General methods for amine synthesis from nitroarenes remain underdeveloped despite their potential advantages 14 16 17 .…”