Alkali Metal–Promoted Facile Synthesis of Secondary Amines from Imines and Carbodiimides

We present here an efficient method for the hydroboration of aldimines (-C=N-) with pinacolborane (HBpin) using an alkali metal catalyst, potassium benzyl. The reaction was accomplished with unprecedented catalytic efficiency under mild and solvent-free conditions to afford the high yield of the corresponding N-boryl amines up to 97%. Various functionalities on aldimines were incorporated for hydroboration. The corresponding boryl amines were subjected to further hydrolysis to yield the corresponding secondary amines with good yields up to 89%. This protocol for the reaction demonstrates an atom-economic and green method with diverse imines that bears excellent functional group tolerance. Chemoselective reduction of imines was also attained, with good yields of 74–89%. We also propose the most plausible mechanism involving the formation of metal hydride as the active pre-catalyst.     

Iron(III) Chloride–Promoted,Solvent‐Free,Facile, and Efficient Friedländer Synthesis of Quinolines

A mild, efficient, and solvent‐free version of Friedländer annulation of 2‐amino ketones and α‐methylene carbonyl compounds for the synthesis of polysubstituted quinolines using a catalytic amount of commercially available iron(III) chloride at room temperature in excellent yields is described.     

Bismuth(III) Chloride–Promoted Efficient Synthesis of Perimidine Derivatives under Ambient Conditions

Various biologically important perimidine derivatives have been efficiently synthesized in excellent yields from naphthalene‐1,8‐diamine and various ketones in the presence of a catalytic amount of BiCl₃.     

A Facile and Efficient Synthesis of Substituted Pyrroles by Three Component Coupling Reaction of Amines, Aldehydes and Nitroalkanes

A facile and efficient synthesis of highly substituted pyrroles has been achieved by a one-pot three-component coupling reaction of aldehyde, amine and nitroalkane by triethyl orthoformate.     

Ferric Chloride Catalyzed Isomerization and Cyclization of Geraniol,Linalood and Nerol

Ferric chloride catalyzes the isomerization and cyclization of geraniol,linalood and nerol in acctonitrile giving α-terpincol in good to high yields.     

Facile and Efficient One-Pot Synthesis of β-Carbolines

Initial formation of tetrahydrocarboline 3 from tryptophan methyl ester 1 and aldehyde 2 by Pictet–Spengler reaction, followed by treatment with trichlorocyanuric acid, provides a facile and efficient route for a one-pot synthesis of β-carbolines with excellent yields.     

Ferric Chloride Catalyzed Isomerization and Cyclization of Geraniol, Linalool and Nerol

Geranyl pyrophosphate, linalyl pyrophosphate and neryl pyrophosphate are known to be important precursors for biosynthesis of cyclic terpenoids, and a variety of cationic intermediates have been suggested to be involved in their skeletal rearrangements1. Ferric chloride has recently been used as a Lewis acid to catalyze Friedel-Crafts reactions2, synthesis of esters and acetals3, a-glycosidation of peracetylated sugars4 and cyclization of 2-(trimethylsilylmethyl) pentadienal5. Therefore, i…     

Stannous Chloride–Promoted Synthesis of S-Allyl-N-aryl Dithiocarbamates under Solvent-Free Conditions

Abstract

A highly efficient method of synthesis of S-allyl-N-aryl dithiocarbamates using SnCl₂ as a catalyst under solvent-free conditions is described. The mild reaction conditions, high yields, and shorter reaction period illustrate the good synthetic utility of this method.     

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.     

Facile tert‐Butoxycarbonylation of Alcohols,Phenols, and Amines using BiCl3 as a Mild and Efficient Catalyst

Facile tert‐butoxycarbonylation of alcohols, phenols, and amines is described by treatment of alcohols, phenols, and amines with di‐tert‐butyl dicarbonate in the presence of a catalytic amount of bismuth(III) chloride, a mild and efficient catalyst, at room temperature in excellent yields.     

Efficient and Facile Synthesis of ( ± )-Salvirecognine

Salvirecognine (7) is a diterpene isolated from Salvia recognita[1] which has been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family. [2] In order to study further relationships between the structure and biological activity of the diterpene compounds and as an extension of diterpenoid synthesis in our laboratory, [3,4] the first total synthesis of the title compound was achieved by an efficient and facile route (Scheme 1).     

Selective Mono‐BOC Protection of Diamines

A facile route for mono‐BOC protection of symmetrical and unsymmetrical diamines was developed by sequential additions of 1 mol of HCl and 1 mol of (BOC)₂O followed by neutralization.     

Iodine- and Indium(III) Chloride–Catalyzed Facile Syntheses of 1,5- and 1,8-Naphthyridines

Iodine- and InCl₃-catalyzed facile syntheses of 1,5- and 1,8-naphthyridines from 3-aminopyridine and 2-aminopyridines are described. The catalyst InCl₃ could be recovered and reused up to five times efficiently.

Cupric Chloride–Catalyzed Synthesis of Symmetrical Azo Compounds from Primary Aromatic Amines

Symmetrical azo compounds were synthesized from primary aromatic amines using n-BuMgBr as a base, oxygen as an oxidant, and CuCl₂ as a catalyst.     

Stannous Chloride Reduction of Nitroalkenes in Amines. Synthesis and Cycloaddition of α-Dialkylaminoaldoxime

α-Dialkylamino aldoximes 12 were prepared by stannous chloride reduction of nitroalkenes in amines. An intramolecular Michael addition-deoxygenation mechanism is suggested. α-Allylamino aldoxime underwent an efficient Intramolecular Oxime Olefin Cycloaddition (IOOC) giving 13     

Ammonium Chloride Promoted Palladium-Catalyzed UIImann Coupling of Aryl Bromide

In water, ammonium chloride was found to promote palladium-catalyzed Ullmann coupling reactions of aryl bromides. In the presence of Pd/C, zinc, NH4Cl, and water, coupling of various aryl bromides was carried out smoothly to afford the corresponding homocoupling products in moderate yields.     

Ammonium Chloride Promoted Palladium-Catalyzed Ullmann Coupling of Aryl Bromide

The Ullmann coupling reaction is one of the most useful methods for the synthesis of symmetrical biaryls. It is usually carried out with copper as a reagent.1 However, it generally requires more than a stoichiomet-ric amount of copper and high reaction temperature. In recent years, various reagents, especially combination of the transition metal with reducing reagents,2-6 were proposed to overcome these problems. For example, Li and co-workers2a,2b have reported the Pd/C and zinc-mediated Ul…     

Solvent Affected Facile Synthesis of Hydroxynaphthyl Ketones: Lewis Acids Promoted Friedel–Crafts and Demethylation Reaction

Hydroxynaphthyl ketones were obtained with high yields under very mild conditions in the presence of AlCl₃ via Friedel–Crafts acylation and demethylation from naphthyl ethers. Several Lewis acids were tested, and AlCl₃ was the most efficient catalyst.     

Ruthenium(III) Chloride–Catalyzed Ring Opening of Epoxides with Aromatic Amines

Ruthenium(III) chloride catalyzes the nucleophilic opening of epoxides by anilines, leading to the efficient synthesis of β‐amino alcohols. High regioselectivity can be considered as a noteworthy advantage of this method.     

A Facile and Efficient Synthesis of (±)-Tropan-2-one

The facile and efficient multigram synthesis of (±)-tropan-2-one 1 was achieved in six steps (65% overall yield) from N-methyl-3-oxopyridyl hydroiodide 3.