Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides

Abstract

The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.

Hydrogenation of Epoxides to Anti‐Markovnikov Alcohols over a Nickel Heterogenous Catalyst Prepared from Biomass (Rice) Waste

“…The ability of nickel catalysts to promote this kind of reaction is well known, and amply described in several publications. [80][81][82] In principle, a direct hydrogenation through hydride transfer from the nickel catalyst (which would make the Lewis/Brønsted sites redundant), [24] cannot be easily ruled out. However, it will be equally hard to prove to which extend this direct hydrogenation competes with the acid-mediated alternative, as the latter species are inherent to the nature of the used bio-derived support.…”

“…It can easily be prepared by oxidation of the corresponding olefin, [20,21] which can be ring‐opened in a reductive fashion to yield anti‐ Markovnikov alcohols. The second, more difficult step can be done by hydrosilylation, [22–24] hydrolysis [25] and transfer hydrogenations [26,27] . The conversion through direct hydrogenation, is more attractive, as it has a higher atom utilization, as demonstrated by some groups in recent years [26,28,29] .…”

NaOH/BEt3 Catalyzed Regioselective Hydroboration of Epoxides to Secondary Alcohols

“…Interestingly, transition‐metal‐catalyzed hydrogenation of terminal epoxides by H 2 as hydrogen source could achieve superior regioselectivities. For instance, when Ni, [4a,b] Co, [5] Iron, [6] Pd [7] or Ti complexes [8] were utilized as catalysts, the desired products obtained were mainly primary alcohols. While Pd/C [9] or Ru complex [10] were utilized, secondary alcohols are the major products (Scheme 1a).…”

Ti(III)-Catalyzed Anti-Markovnikov Reduction of Epoxides with Borohydride

“…In recent years, there have been reports of homogeneous catalysts that give anti-Markovnikov selectivity in the hydrogenation of epoxides (Scheme , A). In these reactions the metal serves as a Lewis acid, catalyzing the rearrangement of the epoxide to a ketone/aldehyde, which is then hydrogenated (or hydroborated) to the anti-Markovnikov alcohol. − In 2019 and 2020, Beller and co-workers introduced this strategy with Fe­(BF 4 ) 2 ·6H 2 O/tetraphos/TFA/H 2 and Co­(NTf 2 ) 2 /triphos/Zn­(OTf) 2 /H 2 . , In 2020, Cavallo, Rueping, and co-workers applied such a reaction to 2,2-disubstituted styrene oxides, and Werner and co-workers have reported such a reaction with an Er/Co catalyst . However, these reactions generally required high temperatures and pressures.…”