Catalytic sp3C–CN Bond Cleavage: Ni-Mediated Phosphorylation of Alkylnitriles

Base-Promoted Nucleophilic Phosphorylation of Benzyl Fluorides via C(sp3)-F Cleavage

Herein, a transition-metal-free phosphorylation of benzyl fluorides with P(O)-H compounds is disclosed. In the presence of tBuOK, various benzyl fluorides react with P(O)-H compounds to produce the corresponding benzyl phosphine oxides, phosphinates, and phosphonates in good to high yields. This base-promoted phosphorylation reaction offers a facile and general strategy for the construction of a C(sp3)-P bond.

Efficient synthesis of α-amino-vinylphosphine oxides from alkyl nitriles via manganese-catalyzed phosphinoenamination

A protocol for the synthesis of α-amino-vinylphosphine oxides by phosphinoenamination reaction between alkyl nitriles and phosphine oxides was developed. The combination of Mn(OAc)2 as a Lewis acid and guanidine as a Lewis base was found to be an efficient catalytic system for this reaction. A series of alkyl nitriles and phosphine oxides are compatible with this conversion, furnishing the desired products in up to 95% yield under mild conditions. Furthermore, this method demonstrates the capability of gram-scale synthesis.

Reductive Coupling of P(O)-H Compounds and Aldehydes for the General Synthesis of Phosphines and Phosphine Oxides

A novel strategy for the selective construction of a C(sp3)-P(III) or -P(V) bond from >P(O)-H compounds and aldehydes is disclosed. By using the H3PO3/I2 system, various secondary phosphine oxides could react with both aromatic and aliphatic aldehydes to afford valuable phosphines (isolated as sulfides) and phosphine oxides in good yields. This method features a wide substrate scope and simple reaction conditions and avoids the use of toxic halides and metals.

Thiourea-Mediated Stereospecific Deoxygenation of Cyanoepoxides to Access Highly Diastereopure Alkenyl Nitriles

A practical and efficient protocol for synthesis of >99% diastereopure Z- and E-alkenyl nitriles is developed, through tetramethylthiourea-mediated stereospecific deoxygenation of respective cis- and trans-cyanoepoxides in ethanol. The desired products are obtained in excellent yields.

Mechanistic Investigation of the Nickel-Catalyzed Transfer Hydrocyanation of Alkynes

The implementation of HCN-free transfer hydrocyanation reactions on laboratory scales has recently been achieved by using HCN donor reagents under nickel- and Lewis acid co-catalysis. More recently, malononitrile-based HCN donor reagents were shown to undergo the C(sp3)-CN bond activation by the nickel catalyst in the absence of Lewis acids. However, there is a lack of detailed mechanistic understanding of the challenging C(sp3)-CN bond cleavage step. In this work, in-depth kinetic and computational studies using alkynes as substrates were used to elucidate the overall reaction mechanism of this transfer hydrocyanation, with a particular focus on the activation of the C(sp3)-CN bond to generate the active H-Ni-CN transfer hydrocyanation catalyst. Comparisons of experimentally and computationally derived 13C kinetic isotope effect data support a direct oxidative addition mechanism of the nickel catalyst into the C(sp3)-CN bond facilitated by the coordination of the second nitrile group to the nickel catalyst.

Nickel-Catalyzed 1,1-Dihydrophosphinylation of Nitriles with Phosphine Oxides

Treatment of phosphine oxides with nitriles usually furnishes 1,2-dihydrophosphinylation products. Herein, we developed a nickel-catalyzed 1,1-dihydrophosphinylation of nitriles with phosphine oxides to access primary amines. This reaction proceeded smoothly under very mild conditions. A series of nitriles and phosphine oxides were compatible with this conversion, and the desired products were obtained in moderate to good yields.

Bromine radical as a visible-light-mediated polarity-reversal catalyst

Polarity-reversal catalysts enable otherwise sluggish or completely ineffective reactions which are characterized by unfavorable polar effects between radicals and substrates. We herein disclose that when irradiated by visible light, bromine can behave as a polarity-reversal catalyst. Hydroacylation of vinyl arenes, a three-component cascade transformation and deuteration of aldehydes were each achieved in a metal-free manner without initiators by using inexpensive N-bromosuccinimide as the precatalyst. Light is essential to generate and maintain the active bromine radical during the reaction process. Another key to success is that HBr can behave as an effective hydrogen donor to turn over the catalytic cycles.

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Using bromine as a polarity-reversal catalyst to generate acyl radicals

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Additive- and metal-free, atom- and step-economic, and operationally simple process

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Using constant light-irradiation to induce and maintain bromine radicals

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Access carbonyl compounds and deuterated aldehydes with wide substrate scope

Nickel-catalyzed coupling of R2P(O)Me (R = aryl or alkoxy) with (hetero)arylmethyl alcohols

α-Alkylation of methyldiarylphosphine oxides with (hetero)arylmethyl alcohols was performed under nickel catalysis. Various arylmethyl and heteroarylmethyl alcohols can be used in this transformation. A series of methyldiarylphosphine oxides were alkylated with 30-90% yields. Functional groups on the aromatic rings of methyldiarylphosphine oxides or arylmethyl alcohols including OMe, NMe2, SMe, CF3, Cl, and F groups can be tolerated. The conditions are also suitable for the α-alkylation reaction of dialkyl methylphosphonates.

Selective C-P(O) Bond Cleavage of Organophosphine Oxides by Sodium

Sodium exhibits better efficacy and selectivity than Li and K for converting Ph₃P(O) to Ph₂P(OM). The destiny of PhNa co-generated is disclosed. A series of alkyl halides R⁴X and aryl halides ArX all react with Ph₂P(ONa) to produce the corresponding phosphine oxides in good to excellent yields.

Lewis Acid Mediated Electrophilic Cyanation of 2,2'-Biphenols

A Lewis acid mediated electrophilic cyanation of 2,2'-biphenols with a trifluoromethanesulfonyl (Tf) protecting group is reported. The cyanation reactions with less toxic, commercially available MeSCN as a cyanating reagent afforded a range of 3-cyan-2,2'-biphenols in moderate to high yields. The use of trifluoromethanesulfonyl (Tf) as a protecting group is crucial to the success of this transformation. Moreover, the cyanated products were readily transformed into various synthetically useful molecules. This protocol features high efficiency, excellent regioselectivity, and good functional group compatibility and may provide a practical tool for the synthesis and modification of biologically active compounds, catalysts, and ligands.

Reductive Cleavage of Unactivated Carbon-Cyano Bonds under Ammonia-Free Birch Conditions

A general protocol for the reductive cleavage of unactivated carbon-cyano bonds in aliphatic nitriles has been achieved under single-electron-transfer conditions using Na/15-crown-5/H₂O. Electron is supplied by the electride derived from bench-stable sodium dispersions and recoverable 15-crown-5. H₂O provides the proton source and suppresses the reduction of aromatic moieties. Compared with the Na/NH₃ electride system generated under traditional Birch conditions, this ammonia-free electride system is more practical and features better reactivity and chemoselectivity for the decyanations of a broad range of aliphatic nitriles.