Facile Synthesis of 2-Aroyl-3,5-diarylthiophene

Abstract

2-Aroyl-3,5-diarylthiophenes were prepared in very good yields by reaction of 2,4,6-triarylpyrylium salts or 2,4,6-triarylthiopyrylium salts with an aqeous solution of sodium sulfide and iodine at room temperature.     

Synthesis of Naphtho[2,1-b]pyrano Pyrrolothiazole Derivatives through 1,3-Cycloaddition Reaction

Facile synthesis of a series of naphtho[2,1,b]pyrano pyrrolo thiazoles was accomplished in good yields in a one-pot reaction through intramolecular 1,3-dipolar cycloaddition of cyclic azomethine ylides with Baylis–Hillman adducts as dipolarophiles. The protocol is applicable to a wide variety of photochromic and biologically active napthopyrano products. The regio- and stereochemical outcome of the cycloaddition reaction was ascertained by x-ray crystallographic study of one of the cycloadducts.     

A Convenient Synthesis of Monosubstituted Ferrocene Heterocycles

An alternative synthesis of monosubstituted ferrocenylheterocyclic compounds, using impure bis(tributylstannyl)ferrocene and heterocyclic bromides as substrates through Pd-catalyzed selective Stille coupling reaction and subsequent destannylation, is described.     

Oxidative oxo Diels–Alder Reactions of Baylis–Hillman Adducts with Electron-Rich Alkenes in the Presence of IBX

Baylis–Hillman adducts were oxidized by iodoxybenzoic acid (IBX) to 2-methylene-1,3-dicarbonyl compounds, which can act as oxodiene to react with electron-rich alkenes to generate a variety of oxo Diels–Alder adducts in good yields.     

The coupling of potassium organotrifluoroborates with Baylis–Hillman derivatives via visible-light photoredox catalysis

Catalyzed by Ir[dF(CF₃)ppy]₂(dtbbpy)PF₆, the coupling of potassium organotrifluoroborates with Baylis–Hillman derivatives under visible light irradiation has been developed. Based on the mechanism of reductive quenching cycle, it provides an easy, mild, efficient method for the synthesis of a variety of α,β-unsaturated carboxylic esters derivatives in a broad scope of the substrates.     

Efficient One-Pot Synthesis of 4-Aroyl-2-pyrones: Nucleophilic Addition of Active Methylene Groups to 1,2-Diaroylacetylenes

An efficient synthesis of 3,6-disubstituted-4-aroyl-2-pyrones in a single-step reaction through Michael addition of 1,2-diaroylacetylenes with active methylene compounds in the presence of NaH in dimethylsulfoxide at room temperature is reported. The structures have been confirmed by spectral data analyses.

Triphenylphosphine-Mediated Synthesis of the E/Z Isomers of Methyl 6-(1,2-Di(methoxycarbonyl))-8-(ethyl Carbamoylformyl)-2-oxo-2H-chromene-4-carboxylate

Triphenylphosphine-mediated reaction of dimethyl acetylenedicarboxylate with ethyl (2-hydroxyphenylcarbamoyl)formate in boiling toluene produces a mixture of methyl 8-(ethyl carbamylformyl)-2-oxo-2H-chromene-4-carboxylate and the E/Z isomers of methyl 6-(1,2-di(methoxycarbonyl)-8-(ethyl carbamoylformyl)-2-oxo-2H-chromene-4-carboxylate in moderate yields.     

Application of Organolithium and Related Reagents in Synthesis. Part 111. Metallation of 2-Methyl- and 4-Methylnicotinic Acids. A Useful Method for Preparation of AZA-Isocoumarins

The metallation (LDA/THF) of 2-methyl- and 4-methylnicotinic acids (1) and (2), and the subsequent reaction of the lithiated species (3) and (4) with carbonyl electrophiles as a synthetic route of 5-aza- and 7-aza-isocoumarins (7), (8), (9) and (10), is described. The isocoumarins (9) and (10) appeared to be readily transformable into the corresponding naphthyridines (11) and (12).     

Novel One Pot Regioselective Multicomponent Synthesis of Highly Functionlaized Spiro Pyrrolidines Through 1,3-Dipolar Cycloaddition Approach

Abstract

One-pot multicomponent synthesis of novel highly functionalized spiro pyrrolidine oxindoles has been accomplished in good yields through 1,3-dipolar cycloaddition reaction of azomethine ylide derived from sarcosine and oxindole with various benzimdazole substituted Baylis–Hillman derivatives. The regiochemical and stereochemical outcome of the multicomponent cycloaddition reaction is ascertained by spectroscopic studies, and one of the products was characterized through x-ray crystallographic analysis.     

Indolizine Studies,Part 5: Indolizine-2-carboxamides as Potential HIV-1 Protease Inhibitors[ 1 ]

1,1-Carbonyldiimidazole-promoted coupling of Baylis–Hillman-derived indolizine-2-carboxylic acids with a range of amine and amino acid derivatives has provided access to the corresponding carboxamides in moderate to excellent yield.     

Stereoselective Synthesis of Functionalized 1,4-Dienes

The article reports a stereoselective synthesis of functionalized 1,4-dienes 5, 6 by coupling allylic Baylis–Hillman acetates 1 and vinyl magnesium chloride at low temperature and in the presence of a catalytic amount of LiCuBr₂ (3%).     

Studies Towards the Synthesis of ATP Analogs as Potential Glutamine Synthetase Inhibitors

In research directed at the development of adenine triphosphate (ATP) analogs as potential glutamine synthetase (GS) inhibitors, adenine and allopurinol derivatives have been synthesized either as novel ATP analogs or as scaffolds for the construction of such analogs.

Elegant Synthesis of Highly Functionalized 1,2,3-Trisubstituted Cyclopentanes

The conversion of cyclic Baylis–Hillman acetates 1 into the corresponding cyano derivatives 2 was achieved using potassium cyanide in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) in aqueous medium. The obtained Michael acceptors 2 easily add primary amines in absolute ethanol to produce a new family of 1,2,3-trisubstituted cyclpentanes 3 in good yields.     

Synthesis of dihydropyrazolo[4,3-c]azepines via iodine-mediated intramolecular hydrative cyclization

A straightforward approach to substituted dihydropyrazolo[4,3-c]azepines via I₂-mediated intramolecular hydration in pyrazole-based allylamines prepared from Morita–Baylis–Hillman adducts of 4-iodopyrazolealdehyes is described.     

Amination of the Baylis–Hillman Acetates in Ethanol

Baylis–Hillman acetates in EtOH were substituted by various nitrogen nucleophiles to give the corresponding trisubstituted alkenes in high yields.     

Environmentally Benign Regio- and Stereoselective Synthesis of Functionalized Tertiary Amines

The environmentally benign, regio‐ and stereoselective synthesis of functionalized tertiary amine 3 from acetates of Baylis‐Hillman adducts with the aliphatic primary amines in the absence of any solvent and catalysts was reported.     

Transition-metal-free nucleophilic allylic substitutions of Morita–Baylis–Hillman bromides with aliphatic and aromatic amines

A simple protocol for the preparation of functionalized allylic amines under mild, transition-metal-free conditions from the reaction of Morita–Baylis–Hillman (MBH) bromides with amines is described herein. The treatment of the MBH bromides with various amines in the presence of NaI and Et₃N in aqueous acetone solution and at room temperature affords the corresponding functionalized allyl amines in moderate to good yields (45–87%). The reaction is rapid and carried out at room temperature.     

Transition metal-free direct nucleophilic α-substitution of Morita–Baylis–Hillman alcohols with amines and thiols

An efficient transition metal-free allylic nucleophilic α-substitution of Morita–Baylis–Hillman alcohols with both aliphatic and aromatic amines in refluxing toluene, using activated molecular sieves as additives, is described herein. The reaction proceeded with exclusive α-regioselectivity in moderate to excellent yields with the formation of water as the sole by-product. Under the same conditions, upon treatment of some thiols with the title substrates, allylic sulfides were obtained in excellent yields and high regioselectivity.     

Synthesis of Novel Oxime Functionalized Aldol Products via Michael Addition of Oximes Onto Baylis–Hillman Adducts

Triphenylphosphine‐catalyzed Michael addition of oximes 2 onto Baylis–Hillman (B‐H) adducts 1 led to an easy access to a novel class of oxime functionalized aldol products 3. This demonstrates the first use of an oxygen‐centered nucleophile in Michael addition to B‐H adducts, without touching any other functional group. Deprotection of oxime in 3 was further demonstrated using molecular hydrogen (1 atm) and 10% Pd/C (cat.) to furnish functionalized 1,3‐diols 4 as potentially useful synthons with optional backbone choice (R³ and EWG).     

Catalytic Effects in Baylis–Hillman Reactions of Chromone-3-carbaldehydes with Acrylonitrile and Methyl Acrylate

The effects of various catalysts, the solvent system, and the temperature on the efficiency and chemoselectivity of reactions of a series of chromone-3-carbaldehydes with acrylonitrile and methyl acrylate are discussed.