A facile Lewis acid-promoted allylation of azetidin-2-ones

Exposure of 3α-chloro-3-phenylthioazetidin-2-ones and allyltrimethylsilane to a Lewis acid promotes a remarkably facile and stereoselective C-3 allylation to give 3α-allyl-3-phenylthioazetidin-2-ones 4 in excellent yield. These allylated azetidin-2-ones undergo smooth desulphurization with tri-n-butyltin hydride or Raney-nickel producing cis-3-allyl- and cis-3-propylazetidin-2-ones.     

Lewis acid promoted annulation of p-quinoneimines by allylsilanes: a facile entry into benzofused heterocycles

[reaction: see text] Lewis acid promoted addition of allyltriisopropylsilane to p-quinoneimines afforded different benzofused heterocycles in moderate to good yields depending on the conditions employed.     

Palladium-catalyzed synthesis of quinoxaline derivatives

A palladium-catalyzed reductive N-heteroannulation of enamines derived from 2-nitrobenzenamines forming mixtures of 1,2-dihydroquinoxalines and 3,4-dihydroquinoxalin-2-ones is described. The reactions are performed using bis(dibenzylideneacetone)palladium(0), 1,3-bis(diphenylphosphino)propane, and 1,10-phenanthroline in DMF under 6 atm of carbon monoxide at 70 °C.     

Triflic acid-promoted aza-Prins-Ritter reaction sequence: a novel synthesis of 4-amidopiperidine derivatives

4-Amidopiperidine derivatives have been prepared for the first time in good yields and with high selectivity by means of aza-Prins-Ritter reaction sequence using 1.2 equiv of triflic acid under mild reaction conditions.     

Lewis acid-promoted direct synthesis of N-unsubstituted hydrazones via the reaction of hydrazine with acetophenone and isatin derivatives

Russian Journal of General Chemistry - Hydrazones 2–22 were synthesized via the reaction of acetophenone with isatin derivatives and anhydrous hydrazine promoted by BF3 as a Lewis acid at...     

Lewis acid-promoted synthesis and reactivity of beta-O-benzylhydroxylamino imides derived from D-glyceraldehyde

This paper describes the synthesis and use of beta-hydroxylamino imides derived from D-glyceraldehyde possessing a number of reactive sites that operate synergistically or alternatively to bring about highly regio- and diastereoselective transformations to give an optically pure aziridine-2-imide, a dihydro pyrimidine-2,4-dione, or a lactone. Both the syntheses, via the diastereoselective 1,4-conjugate addition of O-benzyl hydroxylamine to alpha,beta-unsaturated imides, and transformations can be simply tuned by choosing between different Lewis acids.     

An efficient synthesis of quinoxaline derivatives mediated by stannous chloride

Various biologically important quinoxaline derivatives were efficiently synthesized in excellent yields by the reaction of 1,2‐diketones and 2‐nitroaniline, benzofuroxan or 1,2‐dinitrobenzene promoted by SnCl₂2H₂O. The role of stannous chloride is acting as both reductive agent and catalyst in this synthesis. This new method has the advantages of accessible starting materials, convenient manipulation, short reaction time and high yields.     

Lewis acid-promoted cyclization of heteroatom-substituted enynes

Lewis acid-promoted cyclizations of heteroatom-substituted enynes have been examined. The reaction of enynes and bearing silicon substituents on an alkyne afforded the halogenated five-membered gamma-lactones and gamma-lactams as the main products. The reaction of substrates and having 2-phosphonoacrylate instead of malonate also gave halogenated five-membered cyclic compounds and as the major products. The cyclized products are highly substituted and potentially useful for further synthetic transformations.     

Thiazolium-mediated multicomponent reactions: a facile synthesis of 3-aminofuran derivatives

[reaction: see text] A facile synthesis of highly functionalized 3-aminofuran derivatives by the multicomponent reactions of thiazolium salts, aldehydes, and DMAD is described.     

Lewis acid-promoted imine synthesis by the insertion of isocyanides into C-H bonds of electron-rich aromatic compounds

The Lewis acid-promoted insertion of isocyanides into aromatic C-H bonds is reported. An imine functionality containing an array of N-substituents can be introduced directly into electron-rich aromatics in good yields.     

The facile synthesis of a series of tryptophan derivatives

This study reports a facile method for the synthesis of a variety of 5- and 6-substituted tryptophan derivatives that are difficult to prepare using alternative enzymatic approaches. Acylation of an activated amino acid, derived from serine in situ, is coupled with an enzymatic resolution step to furnish enantiopure analogues bearing a range of electron withdrawing and releasing substituents. Isolation of a dehydroalanine derivative as a by-product from some reactions provides some insights into the likely mechanism of the reaction.     

Microwave-assisted synthesis of quinoxaline derivatives using glycerol as a green solvent

A rapid, efficient, and reliable catalyst-free procedure for the synthesis of quinoxaline derivatives in glycerol under focused microwave irradiation was developed. The reaction proceeded in glycerol without any catalyst making this methodology valuable from both economic and environmental viewpoints.     

Lewis acid-promoted conjugate addition of dienol silyl ethers to nitroalkenes: synthesis of 3-substituted azepanes

A novel gamma-selective conjugate addition of 1-silyl-substituted dienol ethers to nitroalkenes activated by Lewis acids has been developed. The resulting alpha,beta-unsaturated acylsilanes undergo photoinduced protodesilylation to afford the corresponding enals, which can be conveniently transformed into azepanes under appropriate reductive conditions.     

Mild and efficient Lewis acid-promoted detritylation in the synthesis of N-hydroxy amides: a concise synthesis of (-)-Cobactin T

An efficient, high-yielding Lewis acid promoted deprotection of O-trityl hydroxylamine derivatives is described. A range of acid-labile protecting groups, such as N-Boc and O-TBS, were tolerated under these mild conditions. The present method is applicable to the synthesis of a broad range of hydroxylamine derivatives, including N-hydroxy amides (hydroxamic acids), N-hydroxy sulfonamides, and N-hydroxy ureas, which often exhibit significant biological activities. An application of this methodology for a concise synthesis of (-)-Cobactin T (18) is also demonstrated.     

Gallium(III) triflate-catalyzed synthesis of quinoxaline derivatives

Gallium(III) triflate-catalyzed reactions of phenylene-1,2-diamines and 1,2-diketones produce quinoxalines in excellent to quantitative yields. The reactions proceed with 1 mol % catalyst in ethanol at room temperature. The catalyst can be recycled for at least 10 times.     

Keggin type heteropolyacids-catalyzed synthesis of quinoxaline derivatives in water

Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water.This method provides a new and efficient protocol in terms of small quantity of catalyst,a wide scope of substrates,and simple work-up procedure.     

Facile synthesis and anti-proliferative activity evaluation of quinoxaline derivatives

Abstract

A series of “drug-like” compounds based on quinoxaline scaffold with arylsulfonyl hydrazinyl, arylformyl hydrazinyl or arylsulfonyl groups at C-2 and aryloxy groups at C-3, were synthesized in 4 or 5 steps involving cyclization, chlorination and coupling reactions. Cellular anti-proliferative activities of these quinoxaline derivatives in vitro were determined, which revealed that the inhibitory potency and selectivity of 6f was comparable to that of the positive control.     

Fluorine-containing quinoline and quinoxaline styryl derivatives: synthesis and photophysical properties

(E)-2-Styryl-substituted 6,7-difluoroquinolines and quinoxalines were synthesized by the condensation of the corresponding 2-methylbenzazines with aromatic aldehydes. Photoluminescence of the synthesized 6,7-difluoro-2-styrylbenzazines was studied.