Iron‐Catalyzed Hydroboration: Unlocking Reactivity through Ligand Modulation

Abstract

Iron-catalyzed hydroboration (HB) of alkenes and alkynes is reported. A simple change in ligand structure leads to an extensive change in catalyst activity. Reactions proceed efficiently over a wide range of challenging substrates including activated, unactivated and sterically encumbered motifs. Conditions are mild and do not require the use of reducing agents or other additives. Large excesses of borating reagent are not required, allowing control of chemo- and regioselectivity in the presence of multiple double bonds. Mechanistic insight reveals that the reaction is likely to proceed via a highly reactive iron hydride intermediate.

Recent Advances in Hydrometallation of Alkenes and Alkynes via the First Row Transition Metal Catalysis

“…[276] Later, Chirik group, [277] Thomas group, [278] Darcel group, [279] Szymczak group [280] and Webster group [281] independently developed active iron catalysts or precatalysts for this transformation, respectively (Scheme 100b). Interestingly, Zhou et al performed an anti-Markovnikov hydroboration of styrenes with B 2 pin 2 catalyzed by FeCl 2 / t BuOK in the absence of ligand.…”

Syntheses, Structures and Reactivity of Terminal Phosphido Complexes of Iron(II) Supported by a β‐Diketiminato Ligand

“…Reports by Webster et al, , , on the use of an iron(II) β‐diketiminato pre‐catalyst, [(Dippnacnac)Fe(CH 2 TMS)] for the hydrophosphination of unsaturated hydrocarbons and dehydrocoupling of primary and secondary phosphines postulated the formation of an intermediate terminal phosphido complex. In the case of hydrophosphination, the authors proposed that the active catalyst is a monomeric phosphido complex; however, the active species was isolated as a bridging complex, [(Dippnacnac)Fe(PRH(CH 2 ) 3 CH=CH 2 )] 2 .…”

Synthesis and Characterization of Two β-Diketiminato Tin(Ⅳ) Compounds

“…[3,14] It is reasonable to deduce that such activation may be induced from structural isomerization [15] , which is probably due to the active Sn-N bond. [9,15,16] In the formation of 1 and 2, L 1 Li and L 2 Li may act like HC(CPhNPh) 2 Li to form the C 3 N 2 Sn-heterocycle intermediate HC(CMeNAr) 2 SnMe 2 Cl (A) and HC(CMeNAr') 2 -SnMe 3 (B), [12b] respectively. Since the Lewis acidity of the SnMe 2 Cl and SnMe 3 group is weaker than that of the SnX 3 (X＝Cl, Br) groups, the as-formed heterocycles A and B are not stable.…”

“…However, the reaction of L 2 Li and Me 3 SnCl was not stopped here because of the active Sn-CH 3 bond. [12b,12c] The elimination of methane occurred between SnMe 3 moiety of intermediate C and NH proton of adjacent molecule with symmetrical arrangement (Scheme 2), which resulted in an eight-membered ring.…”

“…There has been continued research aimed at the discovery of metal compounds with N-aryl substituted β-diketiminato ligand L 1 H [L 1 ＝ HC(CMeNAr) 2 , Ar ＝ 2,6-i Pr 2 C 6 H 3 ] as some of these compounds can be used as precursors in reactions with various small molecule substrates at the center [1] and efficient homogeneous catalysts. [2] In these researches, most coordination modes of L 1 H can be summarized in four activated modes, [3] including normal N-H activation, [4] backbone Me C-H activation, [5] backbone γ-CH ligation or γ-C-H activation, [6] and a combination of backbone Me and γ-CH C -H activation. [4a,6a] Among which, N-H activation was common due to the relatively rigid N,N-chelation backbone and the demanding N-substituents, [3] while N,C-bonded β-diketiminato compounds were rarely reported.…”