Synthesis of Secondary α-Methylene γ-Lactams

N-trimethylsilyl aldimines, on reaction with the isolated organozinc derivative of ethyl α-(bromomethyl) acrylate, afford secondary α-methylene γ-lactams with quite quantitative yields.     

Synthesis of Potential Cytotoxic α-Methylene γ-Lactams

α-Methylene γ-lactones are known to have physiological activity, especially as cytotoxic agents, and are widely found in nature (1). However they are often toxic which makes them inappropriate for cancer treatment.     

A Short Synthesis of γ-Lactams Via the Spontaneous Ring Expansion of β-Lactams

β-Lactams, derived via the cycloaddition of chlorosulfonyl isocyanate to alkenes, undergo thermal rearrangement at room temperature to afford γ-lactams.     

Synthesis of β-Lactams by Convenient Annelation of Imines

2-Acyl-3-oxo-4,5-benzo-1,2-thiazoline 1,1-dioxide (3) provides good yield routes to monocyclic 3-lactams (6) and tricyclic β-lactams (7) from a variety of imines (4) and 1-substituted-3,4-dihydroisoquinolines (5).     

Synthesis of Benzoxazolinone by Selenium-Catalyzed Carbonylation with Carbon Monoxide

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Catalytic Access to Chiral δ-Lactams via Nucleophilic Dearomatization of Pyridine Derivatives

Nitrogen-bearing rings are common features in the molecular structures of modern drugs, with chiral δ-lactams being an important subclass due to their known pharmacological properties. Catalytic dearomatization of preactivated pyridinium ion derivatives emerged as a powerful method for the rapid construction of chiral N-heterocycles. However, direct catalytic dearomatization of simple pyridine derivatives are scarce and methodologies yielding chiral δ-lactams are yet to be developed. Herein, we describe an enantioselective C4-dearomatization of methoxypyridine derivatives for the preparation of functionalised enantioenriched δ-lactams using chiral copper catalysis. Experimental ¹³C kinetic isotope effects and density functional theory calculations shed light on the reaction mechanism and the origin of enantioselectivity.     

Direct Trapping of Ketene Intermediate by Internal Nucleophile:A New Approach for the Synthesis of γ-Lactams

The application of Wolff rearrangement of the diazoketones derived from α-amino acids has been well documented.¹ It has been generally observed that if the rearrangement is performed in aqueous solution, homologated acid is the expected products, while if the reaction is run in methanol or ammonia, the corresponding homologated ester or amide will be obtained. In connection with other synthetic work, we unexpectedly observed that the Wolff rearrangement of diazoketone 1 in anhydrous methanol gave exclusively γ-lactam 3 in excellent yield.(Scheme 1) The formation of this intramolecular cyclization product was apparently due to the nucleophilic attack of the intermediate ketene 2 by the tosyl protected amino group. Although the solvent methanol can serve as nucleophile, the exclusive formation of γ-lactam indicates the intermolecular nucleophilic attack of the ketene intermediate 2 by methanol is not effective enough to compete with intramolecular nucleophilic attack by the tosyl protected amino group. This observation aroused our interest in the generality of this reaction and its potential as a novel method for the direct synthesis of γ-lactams. We report here the results of the investigation of Wolff rearrangement of several diazoketones derived from N-tosyl protected α-amino acids and β-amino acids.     

An Efficient Synthesis of 2-Oxazolidinones by Palladium-catalyzed Oxidative Carbonylation of β-Aminoalcohols and 2-Aminophenol under Mild Conditions

Oxidative carbonylation of β-aminoalcohols and 2-aminophenol in Pd(OAc)2/I2 catalytic system to produce the corresponding 2-oxazolidinones was conducted with high yields and selectivities in short reaction time. Mild reaction conditions, high catalytic turnover frequency value, improved yields and selectivities are the remarkable features exhibited by this process.     

Synthesis of γ-ketophosphonates via aerobic hydroacylation of vinyl phosphonates

γ-Ketophosphonates are commonly employed as non-hydrolysable phosphate mimetics and as tools in synthesis. The synthesis of γ-ketophosphonates under mild conditions via interception of acyl radicals generated by aldehyde auto-oxidation is described.     

Convenient Synthesis of Aryl Ferrocenyl Ketone via Palladium‐Catalyzed Carbonylation Coupling

A series of aryl ferrocenyl ketones were prepared from iodoferrocene, phenylboronic acids, and CO via palladium‐catalyzed carbonylation coupling in a short time. The procedure was efficient and convenient and avoided formation of diacylated derivatives compared with currently available Friedel–Crafts acylation methodologies.     

Catalytic asymmetric γ-alkylation of carbonyl compounds via stereoconvergent Suzuki cross-couplings

With the aid of a chiral nickel catalyst, enantioselective γ- (and δ-) alkylations of carbonyl compounds can be achieved through the coupling of γ-haloamides with alkylboranes. In addition to primary alkyl nucleophiles, for the first time for an asymmetric cross-coupling of an unactivated alkyl electrophile, an arylmetal, a boronate ester, and a secondary (cyclopropyl) alkylmetal compound are shown to couple with significant enantioselectivity. A mechanistic study indicates that cleavage of the carbon-halogen bond of the electrophile is irreversible under the conditions for asymmetric carbon-carbon bond formation.     

Facile and Efficient Synthesis of γ-Lactone and Butenolide Derivatives

An efficient Baeyer–Villiger rearrangement of cyclobutanone derivatives was investigated. One-pot synthesis of keto-δ-lactone from the Baeyer–Villiger rearrangement products was developed. Meanwhile, the synthetic useful γ-lactone and butenolide derivatives could be easily prepared.     

Efficient Synthesis of Ferrocenylquinolines via the Friedländer Reaction

Acylferrocenes 2a–c reacted with ortho-aminoarylaldehydes 1a–e via the Friedländer condensation reaction to afford the corresponding ferrocenylquinolines 3a–o in moderate yields in the presence of sodium ethoxide (30 mmol%) under mild reaction conditions. Under the same reaction conditions, 1,1′-diacetylferrocene 2d and 1,1′-dipropionylferrocene 2e reacted with ortho-aminoaldehydes 1a–e to afford the corresponding 1,1′-bis(substituted quinolin-2-yl)ferrocene derivatives 3p–t. The structures of compounds 3a–t were determined and characterized by infrared, ¹H NMR, mass spectrometry, and elemental analysis. The crystal structures of 3e and 3q were determined by x-ray crystallography.     

Asymmetric Synthesis. XVIII. Stereocontrolled Synthesis of α-Substituted-2-furfurylamines via Chiral Intermediates

The stereocontrolled synthesis of (R)-α-alkyl-2-fur furylamines (5), using (-)-2-hydroxypinan-3-one (1) as a chiral auxiliary, had been studied. The e. e values of (5) were 91.4->98%, which determined by capillary GC (stationary phase: Chirasil-Val).     

Spirocyclic Amide Acetal Synthesis by [CpRu]-Catalyzed Condensations of α-Diazo-β-Ketoesters with γ-Lactams

The synthesis of spirocyclic amide acetals (33–93 %) has been achieved through Ru(II)-catalyzed condensations of N-carbamate protected pyrrolidinones with metal carbenes derived from α-diazo-β-ketoesters. Thanks to the mildness of the diazo decomposition conditions induced by a 1 : 1 combination of [CpRu(MeCN)₃][BAr_F] and 1,10-phenanthroline, the formation of the sensitive products is possible. Full characterization of this carbonyl-ylide mediated process is provided by DFT calculations.     

A Novel Synthesis of Dimethyl Malonate by Carbonylation of Methyl Chloroacetate Catalyzed by Cobalt Complex

Dimethyl malonate (DMM) is an important organic synthesis intermediate. Traditional synthetic method by reaction of mono-chloroacetic acid with sodium cyanide1 is poisonous and complicated. Therefore, an interest in green synthesis routes of DMM has risen greatly. The several processes for preparing DMM by carbonylation of methyl chloroacetate catalyzed by Co2(CO)8 have been reported2~5. However, Co2(CO)8 is unstable and must be prepared under high pressure (12 Mpa). Moreover, the yield…     

Highly Diastereoselective Synthesis of Functionalized β-Lactams

An efficient method based, on the acid chloride-imine reaction, is reported for the preparation of 1,3-disubstituted β-lactams in good yield and with high selectivity.     

Facile Synthesis of trans-3,4-Diol Derivatives of Substituted Chromans via Catalytic Epoxidation

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