Nickel-Catalyzed Regiodivergent Cyanation of Allylic Alcohols: Scope, Mechanism, and Application to the Synthesis of 1,n-Dinitriles

Nickel-Catalyzed Cyanation of Allylic Alcohols: High Degree of Chiral Inversion in Aqueous Reaction Media

Nickel-catalyzed aqueous cyanation of allylic alcohols is herein described. This catalytic protocol provided environmentally friendly and operationally simple access to a variety of allylic nitriles in good yields. For chiral allylic alcohols, the reaction gave chiral allylic nitriles with a high degree of chiral inversion. The accelerated release of cyanide in H2O was crucial for the success of this reaction.

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

We report a practical and sustainable electrophotochemical metal-catalyzed protocol for decarboxylative cyanation of simple aliphatic carboxylic acids. This environmentally friendly method features easy availability of substrates, broad functional group compatibility, and directly converts a diverse range of aliphatic carboxylic acids including primary and tertiary alkyl acids into synthetically versatile alkylnitriles without using chemical oxidants or costly cyanating reagents under mild reaction conditions.

Harnessing alcohols as sustainable reagents for late-stage functionalisation: synthesis of drugs and bio-inspired compounds

Alcohol is ubiquitous with unparalleled structural diversity and thus has wide applications as a native functional group in organic synthesis. It is highly prevalent among biomolecules and offers promising opportunities for the development of chemical libraries. Over the last decade, alcohol has been extensively used as an environmentally friendly chemical for numerous organic transformations. In this review, we collectively discuss the utilisation of alcohol from 2015 to 2023 in various organic transformations and their application toward intermediates of drugs, drug derivatives and natural product-like molecules. Notable features discussed are as follows: (i) sustainable approaches for C-X alkylation (X = C, N, or O) including O-phosphorylation of alcohols, (ii) newer strategies using methanol as a methylating reagent, (iii) allylation of alkenes and alkynes including allylic trifluoromethylations, (iv) alkenylation of N-heterocycles, ketones, sulfones, and ylides towards the synthesis of drug-like molecules, (v) cyclisation and annulation to pharmaceutically active molecules, and (vi) coupling of alcohols with aryl halides or triflates, aryl cyanide and olefins to access drug-like molecules. We summarise the synthesis of over 100 drugs via several approaches, where alcohol was used as one of the potential coupling partners. Additionally, a library of molecules consisting over 60 fatty acids or steroid motifs is documented for late-stage functionalisation including the challenges and opportunities for harnessing alcohols as renewable resources.

Manganese-catalyzed base-free addition of saturated nitriles to unsaturated nitriles by template catalysis

The coupling of mononitriles into dinitriles is a desirable strategy, given the prevalence of nitrile compounds and the synthetic and industrial utility of dinitriles. Herein, we present an atom-economical approach for the heteroaddition of saturated nitriles to α,β- and β,γ-unsaturated mononitriles to generate glutaronitrile derivatives using a catalyst based on earth-abundant manganese. A broad range of such saturated and unsaturated nitriles were found to undergo facile heteroaddition with excellent functional group tolerance, in a reaction that proceeds under mild and base-free conditions using low catalyst loading. Mechanistic studies showed that this unique transformation takes place through a template-type pathway involving an enamido complex intermediate, which is generated by addition of a saturated nitrile to the catalyst, and acts as a nucleophile for Michael addition to unsaturated nitriles. This work represents a new application of template catalysis for C-C bond formation.

Migratory allylic arylation of 1,n-enols enabled by nickel catalysis

Transition-metal-catalyzed allylic substitution reactions (Tsuji-Trost reactions) proceeding via a π-allyl metal intermediate have been demonstrated as a powerful tool in synthetic chemistry. Herein, we disclose an unprecedented π-allyl metal species migration, walking on the carbon chain involving 1,4-hydride shift as confirmed by deuterium labeling experiments. This migratory allylic arylation can be realized under dual catalysis of nickel and lanthanide triflate, a Lewis acid. Olefin migration has been observed to preferentially occur with the substrate of 1,n-enols (n ≥ 3). The robust nature of the allylic substitution strategy is reflected by a broad scope of substrates with the control of regio- and stereoselectivity. DFT studies suggest that π-allyl metal species migration consists of the sequential β-H elimination and migratory insertion, with diene not being allowed to release from the metal center before producing a new π-allyl nickel species.

Design and synthesis of novel pipernonaline derivatives as anti-austerity agents against human pancreatic cancer PANC-1 cells

Pipernonaline (1), one of the components of the spice pepper, preferentially reduced the survival of human pancreatic cancer PANC-1 cells under nutrient-deprived conditions witha PC₅₀ value of 7.2 μM, suggesting that1couldpotentially lead to the development ofnew anticanceragents basedon theanti-austerity strategy. We have synthesized a total of 31 pipernonaline derivatives, revealing clear structure-activity relationships. Compound 9, which showed the strongest preferential cytotoxicity among synthesized derivatives, inhibited Akt activation and cancer cell migration, making it an extremely promising candidate compound for new pancreatic cancer agents based on the anti-austerity strategy.