Amberlyst-15–Catalyzed Facile Synthesis of α-Amino Phosphonates

A simple and efficient method has been developed for the synthesis of sulfonamide phosphonates from N-tosyl aldimines and dimethyl trimethylsilyl phosphite at 0 °C in the presence of Amberlyst-15 as a heterogeneous catalyst.

Regioselective Synthesis of 1,8-Naphthyridinone-Annulated Oxygen and Sulfur Heterocycles by Tri-n-butyl Tinhydride–Mediated Aryl Radical Cyclization

The tin hydride–mediated cyclizations of a number of ethers, sulfides, and sulfones under mild, neutral conditions have been investigated. While the 2-bromobenzyloxy ethers were prepared in 62–65% yields by the alkylation of 4-hydroxy-1-phenyl-1,8-naphthyridin-2(1H)-one with 2-bromobenzyl bromides in refluxing acetone in the presence of anhydrous potassium carbonate, the sulfides were derived from 4-mercapto-1-phenyl-1,8-naphthyridin-2(1H)-one and 2-bromobenzyl bromides in 82–84% yields by a phase-transfer catalysis (PTC) reaction. The corresponding sulfones were prepared by treatment of the sulfides with m-CPBA in refluxing dichloromethane. The ethers, sulfides, and the sulfones were treated with ⁿ Bu₃SnH-AIBN to give regioselectively 1,8-naphthyridinone-annulated oxygen and sulfur heterocycles in 70–78% yields.     

Amberlyst-15 Catalyzed Addition of Phenols to α,β-Unsaturated Ketones

Amberlyst-15 has been used to catalyze regioselective additions of phenols to α,β-unsaturated ketones in yields of 20–90%. The reaction is superior to the analogous reaction employing concentrated sulfuric acid in affording greater yields and purer products with a minimum of laboratory operations.     

Amberlyst-15–Catalyzed Synthesis of 2-Substituted 1,3-Benzazoles in Water under Ultrasound

A clean and general method has been developed for the synthesis of benzothiazole, benzoxazole, and benzimidazoles using Amberlyst-15 as a recyclable catalyst under ultrasound irradiation in water. The methodology is operationally simple, free from the use of hazardous organic solvents, and does not require the use of inert or anhydrous atmosphere. A number of 1,3-benzazole derivatives were prepared in good to excellent yields by using this methodology.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Bakers' Yeast–Catalyzed Ring Opening of Benzofuroxans: An Efficient Green Synthesis of Aryl-1,2-diamines

A simple and inexpensive method for the reductive cleavage of N–O bond of benzofuroxans with bakers' yeast under nonfermenting condition in aqueous media was achieved. The procedure gives excellent yields of aryl-1,2-diamines.     

Amberlyst-15 Promoted Synthesis of Fused and Spiro γ-Butyrolactones from β-Hydroxyesters

β-hydroxy esters have been converted into fused and spiro γ-butyrolactones in 50–90% yield by refluxing with Amberlyst-15 resin in hydrocarbon solvent. Fused-ring lactones are formed with the cis geometry at the ring junction and the regiochemistry of the closure is that expected from a process proceeding through the most stabilized carbocation. The use of an acidic resin offers several advantages over standard aqueous acid conditions: (1) easier monitoring of the reaction, (2) convenient workup, and (3) higher yields.     

Amberlyst-15 Catalyzed Synthesis of α′-Oxindole-α-Hydroxyphosphonates under Ultrasonic Irradiation

Abstract

An efficient and environment friendly protocol for the synthesis of α′-oxindole–α-hydroxyphosphonates by the condensation of substituted isatin and dialkylphosphite in the presence of amberlyst-15 is reported. This reaction gives good to excellent yields of products under heating and sonication conditions.

Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.     

Stannic Chloride–Iodine: An Efficient Reagent for Regioselective Synthesis of Furan–Fused Heterocycles

SnCl₄‐I₂‐mediated cyclization of ortho‐cyclohexenyl phenol and ortho‐cyclohexenyl enol derivatives of coumarin, uracil, dimedone, and pyrone at room temperature for 1 h give the linear cyclized products in 78–90% yield, which, on treatment with 10% Pd‐C at 250°C for 1–2 h, afford corresponding aromatized products in 80–84% yield.     

An Efficient and Convenient Cyclization Method for the Synthesis of Flavans

Flavansrefertoalargegroupofnaturallyoccurringcompoundspossessinga2-phenyl-chromannucleus.Naturallyoccurringflavansexhibitanumberofimportantbiologicalactivitieswhichifexploitedproperly,mayleadtovaluablenewdrugsoragrochemicals'.Inflavansynthesis,thekeystepistoconstructthe3,4-dihydrobenzopyranring-Variousmethodshavebeendevelopedfortheringformation,butmostoftheminvolvemultiplestepsandgivelowoverallyields2.Inthispaper,BF3wasusedforthefirsttimeasanefficientcatalysttoformthepyranringfroml,3-diaryIp…     

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.     

Imino Diels–Alder Reactions: Efficient Synthesis of Pyrano and Furoquinolines Catalyzed by ZrCl4

Abstract

Anhydrous zirconium tetrachloride is found to be an efficient catalyst for the Imino Diels–Alder reactions of N‐benzylideneanilines with 3,4‐dihydro‐2H‐pyran and 2,3‐dihydrofuran to afford pyrano and furo [3,2‐c] quinolines in good yields.     

Tungstophosphoric Acid–Catalyzed Imino-Diels–Alder Reaction: An Efficient One-Pot Synthesis of Pyrano- and Furanoquinoline Derivatives

Tungstophosphoric acid has been found to be an efficient catalyst for the synthesis of pyranos- and furanoquinolines through the Imino-Diels–Alder reaction involving one-pot coupling of benzaldehydes, anilines, and 3,4-dihydro-2 H-pyran or 2,3-dihydrofuran. The products are formed at room temperature in excellent yields in a short period of time.     

Efficient Synthesis of β‐Amino Alcohols Catalyzed by Niobium Pentachloride: Regioselective Ring Opening of Epoxides with Aromatic Amines

Epoxides undergo a rapid ring‐opening reaction with aromatic amines catalyzed by niobium pentachloride under mild reaction conditions. All the reactions were carried out at room temperature to afford the corresponding β‐amino alcohols in excellent yields and with high regioselectivity.     

Regioselective Synthesis of Coumarin and Quinolone‐Annulated Spiro Heterocycles via Aryl Radical Cyclization

Abstract

3‐(2′‐Bromobenzyloxy)quinolin‐2‐ones and 3‐(2′‐bromobenzyloxy)benzopyran‐7‐ones undergo aryl radical cyclization in the presence of ⁿ Bu₃SnCl‐Na(CN)BH₃‐AIBN to give spiro‐quinolone and coumarin derivatives.     

Aluminium Chloride–Catalyzed Claisen Rearrangement: Synthesis of Polyheterocycles Containing Oxygen,Nitrogen, and Sulfur

Synthesis of 1,8‐naphthyridine‐annulated polyheterocycles containing oxygen, nitrogen, and sulfur has been achieved by thionation and sequential Claisen rearrangement of 4‐(4′‐aryloxybut‐2′‐ynyloxy)‐1‐phenyl[1,8]‐naphthyridin‐2‐ones first by heating in 1,2‐dichlorobenzene for 1–2 h and then by anhydrous AlCl₃‐catalyzed Claisen rearrangement in dichloromethane for 1 h.     

Amberlyst 15®: An Efficient Green Catalyst for the Synthesis of Heterocyclic Compounds

Russian Journal of Organic Chemistry - Amberlyst 15 (A-15) is one of the most common heterogeneous catalysts in organic synthesis. Since its development in 1962, A-15 has proved to be a highly...     

Amberlyst 15–Catalyzed Efficient Synthesis of 2,3‐Unsaturated Glycosides via Ferrier Rearrangement for Glycal

Amberlyst 15 serves as an inexpensive, effective, and environmentally friendly catalyst in converting 3,4,6‐tri‐O‐acetyl‐D‐glucal (1) into 2,3‐unsaturated O‐ and S‐glycosides via Ferrier rearrangement in moderate to excellent yields with high α selectivity.     

Synthesis of γ-sulfonyl δ-lactones and β-sulfonyl styrenes

A facile route to the synthesis of γ-sulfonyl lactones 5 and β-sulfonyl styrenes 6 has been developed, achieving moderate to good yields via the (1) NaH mediated Michael addition of β-ketosulfones 3 and methyl acrylate in refluxing THF and (2) NaBH₄ mediated stereoselective reduction/lactonization of δ-ketoesters 4 in boiling MeOH, or (3) boron trifluoride etherate mediated ring-opening of lactones 5 in MeOH at reflux.     

A Simplified Wittig Synthesis Using a Solid-Liquid Transfer Process : VI - Synthesis of γ -Unsaturated Alcohols from Aromatic and Heteroaromatic Aldehydes

Very good yields can be obtained for the synthesis of γ-unsaturated alcohols without degradation of γ-hydroxylated phosphonium salts using the phase transfer technique in low hydrated solidliquid medium.     

Ceric Ammonium Nitrate (CAN)–Catalyzed Multicomponent Reactions: An Efficient Catalyst for Green Organic Synthesis

Multicomponent reactions (MCRs) consist of two or more synthetic steps carried out without isolation of any intermediate, which reduces time and saves money, energy, and raw materials. The development of MCRs in the presence of ceric ammonium nitrate (CAN) is an efficient approach that meets with requirements of sustainable chemistry. The aim of this review is to highlight the interactive effect of the combined use of MCRs and CAN for the development of new ecofavorable methodologies for synthetic organic chemistry. There are many advantages to the use of CAN as a catalyst in organic synthesis, including the very small amount of this catalyst needed to complete reactions in most cases, lower costs, ecofriendly nature, ease of handling, nontoxicity, and high reactivity.