Synthesis of Novel Derivatives of Pyridine‐2,6‐dicarboxylic Acid

Two series of novel derivatives of pyridine‐2,6‐dicarboxylic acid with potential as polydentate ligands were synthesized from pyridine‐2,6‐dicarboxylic acid. All new compounds were characterized by NMR, MS, IR, and EA.     

Efficient Iodine‐Catalyzed Preparation of Benzylidene Acetals of Carbohydrate Derivatives

An efficient preparation of benzylidene acetals of carbohydrate derivatives catalyzed by iodine has been developed. Yields were excellent in every case.     

Odorless Preparation of Thioglycosides and Thio‐Michael Adducts of Carbohydrate Derivatives

A general, odorless, one‐pot methodology has been developed for the preparation of 1,2‐trans‐thioglycosides and thio‐Michael addition products of carbohydrate derivatives through triphenyl phosphine‐mediated cleavage of disulfides and reaction of the thiolate formed in situ with glycosyl bromides and glycosyl conjugated alkenes.     

Efficient Method for Synthesis of the Derivatives of 5‐Arylidene Barbituric Acid Catalyzed by Aminosulfonic Acid With Grinding

Aminosulfonic acid is an environmentally friendly catalyst. Grinding a mixture of aromatic aldehydes, barbituric acid, and H₂NSO₃H at room temperature (without any solvent) gave 5‐arylidene barbituric acid in high yields, providing a simple and efficient route to synthesis of these compounds.     

Efficient Method for the Synthesis of 1,5‐Benzodiazepine Derivatives Catalyzed by Monoammonium Salt of 12‐Tungstophosphoric Acid

Monoammonium salt of 12‐tungstophosphoric acid [(NH₄)H₂PW₁₂O₄₀] was found to be a practical, inexpensive, reusable, and efficient heterogeneous catalyst for the preparation of 1,5‐benzodiazepine derivatives of o‐phenylenediamine and ketones. The heteropolyacid‐based catalyst has the advantages of simple workup procedure, water insolubility with good activity, and high‐yielding reaction for the synthesis of 1,5‐benzodiazepine derivatives.     

Studies on the Synthesis and Antiproliferative Activities of 13‐cis‐Retinoyl Sugar Derivatives

New retinoyl sugar derivatives of 13‐cis‐retinoic acid were synthesized in three ways in this paper in order to enhance pharmacal effects, especially antiproliferative activities of 13‐cis‐retinoic acid. Their structures were confirmed by IR, ¹H‐NMR, ¹³C‐NMR, and MS spectra and their antiproliferative activities were determined in vitro using human cancer lines. Results showed that some compounds possessed potential antitumor activities.     

Efficient Friedländer Synthesis of Quinoline Derivatives from 2-Aminoarylketones and Carbonyl Compounds Mediated by Recyclable PEG-Supported Sulfonic Acid

2-Aminoarylketones undergo smooth condensation with α-methylene ketones in the presence of 10 mol% of poly(ethylene glycol) (PEG)–supported sulfonic acid under mild reaction conditions to afford the corresponding poly-substituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective, and environmentally benign.     

Synthesis of Novel Pyran β-Amino Acid and 5,6-Dihydro-2H-pyran β-aminoxy Acid from Carbohydrate Derivatives

Synthesis of two new amino acids, containing pyran rings, is reported from carbohydrate derivatives. The cis-3-amino-pyran-2-carboxylic acid (cis-APyC) was prepared from (R)-glyceraldehyde derivative, using nucleophilic substitution reaction for pyran ring formation. Similarly, the trans-3-aminoxy-5,6-dihydro-2H-pyran-2-carboxylic acid (trans-AmPyC) was prepared from diacetone glucose (DAG), using ring closing metathesis (RCM) reaction for the ring formation.     

Direct Synthesis of α-Amino Acid Derivatives by Hydrative Amination of Alkynes

α-Amino acid derivatives are key components of the molecules of life. The synthesis of α-amino carbonyl/carboxyl compounds is a contemporary challenge in organic synthesis. Herein, we report a practical method for the preparation of α-amino acid derivatives via direct hydrative amination of activated alkynes under mild conditions, relying on sulfinamides as the nitrogen source. Computational studies suggest that the reaction is enabled by a new type of sulfonium [2,3]-sigmatropic rearrangement.     

Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives Catalyzed by p-Dodecylbenezenesulfonic Acid in Water

With the increasing concerns of the environment, more and more chemists are devoted to the research of the "green synthesis" which means that the reagent, solvent and catalyst are environmentally friendly in the organic chemical reactions. The importance of aqueous reaction is now generally recognized, and development of carbon-carbon bond-forming reactions that can be carried out in aqueous media is now one of the most challenging topics in organic synthesis.[1]Herein, we report a clean synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxo-octahydroxanthene derivatives from aromatic aldehyde and 5,5-dimethyl-1,3-cyclohexadione using p-dodecylbenezenesulfonic acid (DBSA) as the catalyst in water.This method provides several advantages such as high yield, simple work-up procedure and environmental friendliness and water was chosen as a green solvent. All the products were characterized by m.p., 1H NMR, IR and elemental analyses.     

Synthesis of β–Amino Acid Derivatives

In recent years, β-amino acids and their derivatives have attracted considerable attention due to their occurrence in biologically active natural products, such as dolastatins, cyclohexylnorstatine and Taxol. β–Amino acids also find application in the synthesis of β–lactams, piperidines, indolizidines. Moreover, the peptides consisting of β–amino acids, the so-called β–peptides, have been extensively studied recently. Consequently, considerable efforts have been directed to the synthe…     

Synthesis of Novel Carbohydrate Acridinone Derivatives with Potential Biological Activities using 1,3‐Dipolar Cycloaddition

Novel 10‐{[3‐(6‐hydroxy‐2,2‐dimethyltetrahydrofuro[2,3‐d][1,3]dioxol‐5‐yl)‐4,5‐dihydro‐5‐isoxazolyl]methyl}‐9(10H)‐acridinone derivatives (13–16) were synthesized by 1,3‐dipolar cycloaddition using the carbohydrate derivative as dipole and different 10‐allyl‐9(10H)‐acridinone derivatives (9–12) as dipolarophiles. The new cycloadducts as well as the dipolarophiles precursors were characterized spectroscopically.     

Versatile Sugar Derivatives for the Synthesis of Potential Degradable Hydrophilic‐Hydrophobic Polyurethanes and Polyureas

Biodegradable polymers obtained from renewable natural sources are currently receiving increasing attention because they are an alternative to the traditional petroleum‐based plastics. In the present communication we describe the synthesis of the diol monomers 2,3,4‐tri‐O‐benzyl‐L‐arabinitol (ABnOH) and 2,3,4‐tri‐O‐benzylxylitol (XBnOH), and the diamino monomers 1,5‐diamino‐1,5‐dideoxy‐2,3,4‐tri‐O‐benzyl‐L‐arabinitol (ABnNH ₂ ) and 1,5‐diamino‐1,5‐dideoxy‐2,3,4‐tri‐O‐benzylxylitol (XBnNH ₂ ), which can be used in the preparation of new potentially biodegradable sugar‐based polymers. As an example, we describe the synthesis and characterization of a polyurethane [PU‐(ABnOH‐HMDI)] and a polyurea [PUR‐(ABnNH₂‐HMDI)] by poly addition reaction of ABnOH and ABnNH ₂ with 1,6‐hexamethylene diisocyanate.      

A New Route of Synthesis of 5‐(N‐Phenethylamino)salicylic Acid Derivatives by Rapid and Selective Reduction of the Amide Group with NaBH4/Acetic Acid

A good yield of 5‐(N‐phenethylamino)salicylic acid derivatives was successfully obtained from the corresponding methyl 2‐acetoxy‐5‐(N‐phenethylamino)benzoate esters by rapid and selective reduction of the amide group in the acyl protected salicylic acid with NaBH₄/acetic acid in dioxane followed by hydrolysis of the ester group.     

1,6‐C‐H and 1,5‐O‐Si Insertion Reactions of Alkylidenecarbene Derivatives of Monosaccharides*

A new protocol has been developed for the generation of alkylidenecarbene derivatives of monosaccharides based on the reaction of trimethylsilylazide and Bu₂SnO with α‐cyanomesylates derived from uloses. When this method is applied to conveniently functionalized carbohydrate derivatives it provides novel heterocyclic ring systems by the rare 1,6‐C‐H or 1,5‐O‐Si insertion reactions.     

Synthesis of C‐3 Branched Allyl and Pentadienyl Glucosamines via Radical Coupling of Sugar‐Thionocarbonates

Abstract

The intermolecular AIBN‐promoted free radical reaction of glucosamine thionocarbonates as radical donors, and allyl or pentadienyl‐tributyltin reagents gave the expected C‐3 branched sugar derivatives in good yield and with total equatorial selectivity.     

Enantioselective Synthesis of β-Amino Acid Derivatives Enabled by Ligand-Controlled Reversal of Hydrocupration Regiochemistry

A Cu-catalyzed enantioselective hydroamination of α,β-unsaturated carbonyl compounds for the synthesis of β-amino acid derivatives was achieved through ligand-controlled reversal of the hydrocupration regioselectivity. While the hydrocupration of α,β-unsaturated carbonyl compounds to form α-cuprated species has been extensively investigated, we report herein that, in the presence of an appropriate ancillary chiral ligand, the opposite regiochemistry can be observed for cinnamic acid derivatives, leading to the delivery of the copper to the β-position. This copper can react with an electrophilic aminating reagent, 1,2-benzisoxazole, to provide enantioenriched β-amino acid derivatives, which are important building blocks for the synthesis of natural products and bioactive small molecules.     

Synthesis of Bis‐1,4‐Dihydropyridine Derivatives

Abstract

A series of bis‐1,4‐dihydropyridine derivatives were synthesized by the reaction of p‐phenylenedialdehyde or m‐phenylenedialdehyde and active methylene compounds.     

Effective Conversion of Three Diacetyl‐C‐(β‐D‐Glycopyranosyl) Phloroglucinols to Spiroketal Derivatives by Refluxing in Water

Refluxing of diacetylphloroglucinol C‐β‐D‐gluco‐, ‐galacto‐, and ‐allopyranosides in water for 1 d gave two kinds of spiroketal derivatives in total yields of 77%, 74%, and 64%, respectively. The structure and stereochemistry of the six new spiro(benzofuran‐[2H]pyran and ‐[2H]furan) derived from galactoside and alloside were verified by NMR analysis. The production ratios of the spiro derivatives were measured by HPLC analysis at regular time intervals. Since the majority of spiro(benzofuran‐[2H]furan) were produced after 8 to 12 h of refluxing and most spiro(benzofuran‐[2H]pyran) produced after 2 d of refluxing, it is assumed that formation of spirofuran and spiropyran is a kinetic‐ and thermodynamic‐controlled reaction, respectively.     

Unusual p‐Toluene Sulfonic Acid–Catalyzed Carbon–Carbon Bond Formation

Abstract

Attempts to synthesize the antidepressant drug atomoxetine directly by p-TSA‐catalyzed reaction between o‐cresol and N‐methyl‐3‐phenyl‐3‐hydroxypropyl amine in toluene at reflux temperature surprisingly resulted in the formation of ortho‐substituted phenol derivative. The structure is unambiguously confirmed by single crystal X-ray.