Three-component carbon–carbon bond-forming reactions catalyzed by a Brønsted acid–surfactant-combined catalyst in water

3-Allyl-N-(alkoxycarbonyl)indoles are synthesized via the reaction of 2-(alkynyl)phenylisocyanates and allyl carbonates in the presence of Pd(PPh3)4 (1 mol %) and CuCl (4 mol %) bimetallic catalyst. It is most probable that Pd0 acts as a catalyst for the formation of a π-allylpalladium alkoxide intermediate and CuI behaves as a Lewis acid to activate the isocyanate, and the cyclization step proceeds with a cooperative catalytic activity of Pd and Cu. On the other hand, N-(alkoxycarbonyl)indoles are produced via the reaction of 2-(alkynyl)phenylisocyanates and alcohols under a catalytic amount of Na2PdCl4 (5 mol %) or PtCl2 (5 mol %). PdII or PtII catalyst exhibits dual roles; it acts as a Lewis acid to accelerate the addition of alcohols to isocyanates and as a typical transition-metal catalyst to activate the alkyne for the subsequent cyclization.

A bimetallic catalyst and dual role catalyst: synthesis of N-(alkoxycarbonyl)indoles from 2-(alkynyl)phenylisocyanates.

A new attempt was investigated to utilize inorganic solid acids and bases for the promotion of the reaction of cyanotrimethylsilane (Me3SiCN) with carbonyl compounds. Strongly acidic solids, such as Sn4+ ion-exchanged montmorillonite (Sn-Mont) and Fe3+ ion-exchanged montmorillonite (Fe-Mont), as well as basic solids, such as calcium fluoride (CaF2), hydroxyapatite (HAp), calcium oxide (CaO), and magnesium oxide (MgO), catalyzed the reaction of Me3SiCN with aldehydes and ketones to afford the corresponding 2-(trimethylsiloxy)alkanenitriles in good yields. The reactions of dimethyl acetals with Me3SiCN in the presence of solid acids afforded 2-methoxyalkanenitriles. In cyanosilylations of α,β-unsaturated ketones two kinds of adducts were produced selectively, depending on the use of a solid acid or a solid base: 1,4-Adducts (trimethylsilyl enol ether forms) were selectively obtained in the presence of strong solid acids, such as Fe-Mont and Sn-Mont, while 1,2-adducts (trimethylsilyl ether forms) were predom...

Solid Acid and Base-Catalyzed Cyanosilylation of Carbonyl Compounds with Cyanotrimethylsilane

Publisher Summary Organic chemistry includes a large number of distinctive reactions and a wide variety of reaction types. Given the physical properties of an organic reactant, there is no quantitative means for predicting a priori how it can react. As a result, organic chemistry depends heavily on linear free-energy relationships (LFER) to correlate the various reactivity trends of structurally related compounds. This chapter describes the donor/acceptor organizations and the electron-transfer paradigm for chemical reactivity. Electron donors (D) and electron acceptors (A) constitute reactant pairs that are traditionally considered with more specific connotations in mind—such as nucleophile/electrophile in bond formation, reductant/oxidant in electron transfer, and base/acid in adduct production. The electron-transfer paradigm provides a unifying mechanistic basis for various bimolecular reactions via the identification of nucleophiles as electron donors and electrophiles as electron acceptors. Such a reclassification of a nucleophile/electrophile, an anion/cation, a base/acid, or a reductant/oxidant pair under a single donor/acceptor rubric offers a number of advantages leading to the quantitative prediction of reaction rates.

Donor/acceptor organizations and the electron-transfer paradigm for organic reactivity

Low valent ruthenium hydride complexes are excellent catalysts which act as either redox Lewis acid or base catalysts. Nitriles are substrates which have strong coordination ability towards transition metals, so new types of catalytic transformations of nitriles have been explored using these catalysts. As redox Lewis acid catalysts, hydration of nitriles, amidation of amines, and esterification of alcohols with nitriles can be achieved. The same catalyst can be used for direct formation of carbon nucleophiles by C–H activation of pronucleophiles, such as nitriles and carbonyl compounds, hence catalytic aldol-type reactions and Michael-type additions can be performed under neutral and mild conditions.

A New Way for Efficient Catalysis by Using Low Valent Ruthenium Complexes as Redox Lewis Acid and Base Catalysts

In the presence of a catalytic amount of a transition metal compound such as [Rh(COD)Cl]2, Co(acac)2, or NiCl2, trimethylsilyl cyanide smoothly reacts with acetals to form α-methoxy carbonitriles in good yields. In the coexistence of catalytic amounts of [Rh(COD)Cl]2 and TMS-CN, silyl enol ethers or ketene silyl acetals react with acetals, aldehyes, or imines to yield the corresponding coupling products in good yields under almost neutral conditions.

Efficient Activation of Acetals, Aldehydes, and Imines toward Silylated Nucleophiles by the Combined Use of Catalytic Amounts of [Rh(COD)Cl]2 and TMS-CN under Almost Neutral Conditions

In the presence of a catalytic amount of trityl perchlorate, trimethylsilyl cyanide reacts with the dimethyl acetals of chalcone derivatives, with simultaneous double bond isomerization, to yield γ-methoxy-α,β-unsaturated carbonitriles Trimethylsilyl sulfides react with dimethyl acetals derived from α,β-unsaturated ketones to yield 1,3-bis(alkylthio)propene derivatives under similar conditions

Reactions of α,β-Unsaturated Ketone Acetals with Trimethylsilyl Cyanide and Trimethylsilyl Sulfides

In the presence of a catalytic amount of [Rh(COD)Cl]2 or trityl perchlorate, trimethylsilyl cyanide smoothly reacts with (E)-chalcone dimethyl acetal to yield (Z)-2,4-diphenyl-2-methoxy-3-butenenit...

Efficient Method for the Preparation of (Z)-α-Alkoxy-β,γ-unsaturated Nitriles Starting from the Corresponding Acetals of (E)-Chalcone Derivatives

Efficient Activation of Acetals, Aldehydes, and Imines Toward Silylated Nucleophiles by the Combined Use of Catalytic Amounts of (Rh( COD)Cl)2 and TMS-CN Under Almost Neutral Conditions.

Effective Activation of Acetals Toward Nucleophiles by the Use of Transition Metal Salts. New Method for Cyanation of Acetals and Ortho Esters Derived from Aromatic and α,β-Unsaturated Carbonyl Compounds with Trimethylsilyl Cyanide Un

T. Soga

Papers

Efficient Activation of Acetals, Aldehydes, and Imines toward Silylated Nucleophiles by the Combined Use of Catalytic Amounts of [Rh(COD)Cl]2 and TMS-CN under Almost Neutral Conditions

Reactions of α,β-Unsaturated Ketone Acetals with Trimethylsilyl Cyanide and Trimethylsilyl Sulfides

Efficient Method for the Preparation of (Z)-α-Alkoxy-β,γ-unsaturated Nitriles Starting from the Corresponding Acetals of (E)-Chalcone Derivatives

Efficient Activation of Acetals, Aldehydes, and Imines Toward Silylated Nucleophiles by the Combined Use of Catalytic Amounts of (Rh( COD)Cl)2 and TMS-CN Under Almost Neutral Conditions.

Effective Activation of Acetals Toward Nucleophiles by the Use of Transition Metal Salts. New Method for Cyanation of Acetals and Ortho Esters Derived from Aromatic and α,β-Unsaturated Carbonyl Compounds with Trimethylsilyl Cyanide Un