Electron-deficient Alkynes Research Articles

Acetoxypalladation of unactivated alkynes and capture with alkenes to give 1-acetoxy-1,3-dienes taking dioxygen as terminal oxidant

A new and general protocol for the synthesis of 1-acetoxy-1,3-dienes by an acetoxypalladation/Heck cross-coupling/β-H elimination tandem process is described in which dioxygen is the terminal oxidant. Electron-rich and electron-deficient alkynes are both effective substrates in this system. It is the first example of acetoxypalladation of diarylalkynes.

Regioselective Rhodium(II)‐Catalyzed Hydroaminations of Propargylguanidines

Regioselective Rhodium(II)‐Catalyzed Hydroaminations of Propargylguanidines

ChemInform Abstract: Iron‐Catalyzed Domino Process for the Synthesis of α‐Carbonyl Furan Derivatives via One‐Pot Cyclization Reaction.

The Fe(ClO4)3-catalyzed intramolecular rearrangement/cyclization/oxidation reaction sequence for the synthesis of α-carbonyl furan derivatives from electron-deficient alkynes and 2-yn-1-ols is reported.

Development of benzothiazole ‘click-on’ fluorogenic dyes

‘Click-on’ fluorogenic reaction: a non-fluorescent benzothiazole with an electron-deficient alkyne group at 2-position reacts with azide containing molecules could form fluorescent adducts.

ChemInform Abstract: Cationic Rhodium(I) Complex-Catalyzed [3 + 2] and [2 + 1] Cycloadditions of Propargyl Esters with Electron-Deficient Alkynes and Alkenes.

A variety of acyloxy-substituted tertiary propargyl esters undergo the title cycloaddition reaction with acetylenedicarboxylates to give cyclopentadienetricarboxylates.

ChemInform Abstract: Synthesis of Quinazoline Derivatives Through Anionic Cycloaddition Reactions of Methyl 2,4-Dimethoxy-6-methyl-5-pyrimidinecarboxylate with Acetylenes and Olefins.

The anionic cycloaddition of methyl 2,4-dimethoxy-6-methyl-5-pyrimidinecarboxylate has been investigated. The lithium salt of methyl 2,4-dimethoxy-6-methyl-5-pyrimidinecarboxylate, generated by deprotonation with lithium diisopropylamide in ether at – 70°, reacted smoothly with electron deficient acetylenes and olefins to give quinazoline derivatives in a single step.

ChemInform Abstract: Iodine Atom Transfer Addition Reactions with Alkynes. Part 1. Alkyl Iodides.

Abstract Simple 2° - and 3° -alkyl iodides add smoothly to electron deficient alkynes under standard atom transfer conditions 10% Bu 3 SnSnBu 3 , sunlamp photolysis. Mechanistic experiments help to interpret stereochemical and yield trends, and a new model for atom abstraction reactions of rapidly inverting a-vinyl radicals is proposed.

Multicatalytic, asymmetric Michael/Stetter reaction of salicylaldehydes and activated alkynes

We report the development of a multicatalytic, one-pot, asymmetric Michael/Stetter reaction between salicylaldehydes and electron-deficient alkynes. The cascade proceeds via amine-mediated Michael addition followed by an N-heterocyclic carbene-promoted intramolecular Stetter reaction. A variety of salicylaldehydes, doubly activated alkynes, and terminal, electrophilic allenes participate in a one-step or two-step protocol to give a variety of benzofuranone products in moderate to good yields and good to excellent enantioselectivities. The origin of enantioselectivity in the reaction is also explored; E/Z geometry of the reaction intermediate as well as the presence of catalytic amounts of catechol additive are found to influence reaction enantioselectivity.

Iron-Catalyzed Domino Process for the Synthesis of α-Carbonyl Furan Derivatives via One-Pot Cyclization Reaction

The Fe(ClO(4))(3)-catalyzed intramolecular rearrangement/cyclization/oxidation reaction sequence for the synthesis of alpha-carbonyl furan derivatives from electron-deficient alkynes and 2-yn-1-ols is reported.

Nano‐Cu2O‐Catalyzed Formation of CC and CO Bonds: One‐Pot Domino Process for Regioselective Synthesis of α‐Carbonyl Furans from Electron‐Deficient Alkynes and 2‐Yn‐1‐ols

The formation of carbon-carbon and carbon-oxygen bonds continues to be an active and challenging field of chemical research. Nanoparticle catalysis has attracted considerable attention owing to its environmentally benign and high activity toward the reactions. Herein, we described a novel and effective nano-Cu(2)O-catalyzed one-pot domino process for the regioselective synthesis of α-carbonyl furans. Various electron-deficient alkynes with 2-yn-1-ols underwent this process smoothly in moderate to good yields in the presence of air at atmospheric pressure. It is especially noteworthy that a novel 2,4,5-trisubstituted 3-ynylfuran was formed in an extremely direct manner without tedious stepwise synthesis. Additionally, as all of the starting materials are readily available, this method may allow the synthesis of more complex α-carbonyl furans. An experiment to elucidate the mechanism suggested that the process involved a carbene intermediate.

ChemInform Abstract: Synthesis and Chemistry of Fullerene Derivatives Bearing Phosphorus Substituents. Unusual Reaction of Phosphines with Electron-Deficient Acetylenes and C60.

A unique method to introduce phosphorus substituents onto C60 is based on the reaction of phosphines with acetylenes and C60. Treatment of C60 with phosphines (PR3) and electron-deficient acetylenes (A) in toluene at ambient temperature gave fullerene derivatives (1, R = C6H5 and A = MeO2CC⋮CCO2Me; 2, R = C6D5 and A = MeO2CC⋮CCO2Me; 3, R = C6H5 and A = EtO2CC⋮CCO2Et; 4, R = p-CH3C6H5 and A = MeO2CC⋮CCO2Me; 6, R = C6H5 and A = trans-MeO2CC⋮CCHCHCO2Me) consisting of a phosphorus ylide group and a cyclopropane ring on the fullerene moiety in good to excellent yields. The structures of these ylide derivatives are determined on the basis of their spectral data and single-crystal X-ray diffraction measurements. All these ylides show temperature-dependent NMR spectra that can be rationalized on the basis of interchange between two Z,E isomers and restricted rotation of the substituents on the fullerene moiety. Based on the known chemistry of phosphines and acetylenes, we propose a mechanism to account for the fo...

ChemInform Abstract: 1,3-Dipolar Cycloaddition of Azomethine Ylides Derived from Imines and Difluorocarbene to Alkynes: A New Active Pb-Mediated Approach to 2-Fluoropyrrole Derivatives.

Domino reactions of imines with difluorocarbene in the presence of electron-deficient alkynes lead to 2-fluoropyrrole derivatives. The process involves intermediate azomethine ylide formation, its 1,3-dipolar cycloaddition to alkyne, followed by dehydrofluorination. A modified difluorocarbene generation method using active lead for dibromodifluoromethane reduction is proposed, providing shorter reaction time and improved yields of fluoropyrroles. The reactions with monoactivated acetylenes occur regioselectively. The cycloaddition of ylides to dipolarophiles such as phenylpropynal, whose carbonyl group is more active than the triple bond, gives rise to oxazolidine derivatives, implying a change in the reaction site.

Cationic Rhodium(I) Complex-Catalyzed [3 + 2] and [2 + 1] Cycloadditions of Propargyl Esters with Electron-Deficient Alkynes and Alkenes

A cationic rhodium(I) complex, [Rh(cod)(2)]SbF(6), catalyzes the [3 + 2] cycloaddition of propargyl esters with dialkyl acetylenedicarboxylates in good yields, presumably through carbonyl-stabilized cationic rhodium(I) alkenylcarbene intermediates. The same rhodium(I) complex also catalyzes the [2 + 1] cycloaddition (cyclopropanation) of propargyl esters with N,N-disubstituted acrylamides in good yields with perfect diastereoselectivity.

Benzoheterocycle Synthesis via Diphosphine Catalysis

The authors reported a method to construct seven different types of ­benzo-fused heterocyles 3 - indolines, dihydro­pyrrolopyridines, benzimidazolines, dihydrobenzo-3,1-oxazines, benzomorpholines, tetrahydroquinolines, and tetrahydroisoquinolines - from simple dinucleophiles 1 and electron-deficient acetylenes 2. Diphenyl­phosphinopropane (DPPP) is an efficient catalyst for this mixed double Michael addition process. In some cases the addition of the AcOH-NaOAc pair can further increase the yields.

Orthogonal Synthesis of Densely Functionalized Pyrroles and Thiophenes from the Reactions of Imidazo[1,5-a]pyridine Carbene-Derived Zwitterions with Electron-Deficient Alkynes

1-Thiocarbamoyl imidazo[1,5-a]pyridinium inner salts, which were obtained readily from the addition of C,N-substituted heterocyclic carbenes imidazo[1,5-a]pyridine-1-ylidenes to isothiocyanates, are powerful ambident nucleophilic zwitterions. They acted as nitrogen nucleophiles toward ethyl propiolate to produce polyfunctionalized pyrrole derivatives in high yields. When treated with dimethyl acetylenedicarboxylate, they behaved exclusively as sulfur nucleophiles to afford fully substituted thiophenes in excellent yields. This work provides highly efficient orthogonal synthesis of polyfunctionalized pyrroles and thiophenes that were not easily obtained by other chemical means.

Diphosphine-catalyzed mixed double-Michael reaction: a unified synthesis of indolines, dihydropyrrolopyridines, benzimidazolines, tetrahydroquinolines, tetrahydroisoquinolines, dihydrobenzo-1,4-oxazines, and dihydrobenzo-3,1-oxazines.

Seven different types of benzannulated N-heterocycles-indolines, dihydropyrrolopyridines, benzimidazolines, dihydrobenzo-3,1-oxazines, benzomorpholines, tetrahydroquinolines, and tetrahydroisoquinolines-can be obtained from simple dinucleophiles and electron-deficient acetylenes in one synthetic step. This powerful methodology was made possible through the use of diphenylphosphinopropane (DPPP) as the catalyst, with acetic acid and sodium acetate used as additives in some cases. The benzannulated N-heterocycles were isolated in excellent yields under mild metal-free conditions; they were purified without the need for aqueous workups.

Gold-Catalyzed Ethynylation of Arenes

A novel gold-catalyzed ethynylation of aromatic rings with electron-deficient alkynes via gold catalyzed C-H activation of both C(sp)-H and C(sp(2))-H bonds has been developed. This transformation provides aromatic propiolates difficult to prepare by other methods, highlighting the synthetic potential of gold chemistry.

Michael Addition-Lactonization Reaction of Electron-Deficient Alkynes with N-(Diphenylmethylene)glycinates: An Efficient Synthesis of 3-Amino-2-pyrone Derivatives

A mild and efficient process for the synthesis of 3-amino-2-pyrone derivatives has been developed. This approach is based on the Michael addition of N-(diphenylmethylene)glycinates to various alkynyl ketones, followed by lactonization using 10 mol% sodium hydroxide as catalyst. Aromatic and aliphatic alkynyl ketones were converted into the corresponding 3-amino-2-pyrone derivatives in moderate to high yields. When methyl propiolate was submitted to the reaction, α,β-dehydroamino acids were formed in good yields.

Hydroalkylation leading to heterocyclic compounds (Part 2): practical synthesis of polysubstituted 1,2,3,4-tetrahydropyridines through multicomponent reactions (MCRs)

Polysubstituted 1,2,3,4-tetrahydropyridines were synthesized through hydroalkylation of electron-deficient alkynes, followed by double Mannich addition reactions, which is a practical protocol with atom efficiency and good substrate scope.

Synthesis of Functionalized l-Cysteine and l-Methionine by Reaction with Electron-Deficient Acetylenes

A novel families of nonconventionally functionalized amino acids have been synthesized in almost quantitative yields by chemo-, regio- and stereospecific addition of L -cysteine and L -methionine to electron-deficient functionalized acetylenes (cyano-acetylenes and methyl 4-hydroxy-4-methylpent-2-ynoate) under mild conditions (water, r.t., 2―5 h). Thus, for the first time, the uncommonly functionalized optically active amino acids composing of L-cysteine and L -methionine structural units along with cinnamic acid, dihydrofuranone, iminodihydrofuran, and other biologically important functionalities are readily available.