An Efficient Synthesis of Thioesters Via TFA-Catalyzed Reaction of Carboxylic Acid and Thiols: Remarkably Facile C–S Bond Formation

Abstract

A general, facile, and efficient new synthetic path to thioesters was established by employing defined TFA-catalyzed reaction of carboxylic acid and thiol under mild conditions. The structure of the newly synthesized compounds was determined by infrared spectroscopy, nuclear magnetic resonance, and a single crystal X-ray crystallographic analysis.

Supplemental materials are available for this paper. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

RASS-Enabled S/P−C and S−N Bond Formation for DEL Synthesis

DNA encoded libraries (DEL) have shown promise as a valuable technology for democratizing the hit discovery process. Although DEL provides relatively inexpensive access to libraries of unprecedented size, their production has been hampered by the idiosyncratic needs of the encoding DNA tag relegating DEL compatible chemistry to dilute aqueous environments. Recently reversible adsorption to solid support (RASS) has been demonstrated as a promising method to expand DEL reactivity using standard organic synthesis protocols. Here we demonstrate a suite of on-DNA chemistries to incorporate medicinally relevant and C−S, C−P and N−S linkages into DELs, which are underrepresented in the canonical methods.     

A Facile and Efficient Synthesis of Arylsulfonates and Arylsulfonyl Hydrazides under Solvent Free Conditions

Organosulfur compounds are useful materials and most of them have pharmacological properties. The sulfonic esters are important intermediates in organic synthesis and used as acaricides and thermal recording materials. The sulfonyl hydrazides are valuable as inhibitors, agrochemical fungicides, insecticides and photographic images. Some methods have been reported for preparing these compounds to date. Usually, these reactions were carried out in organic solvent[1,2]such as pyridine and DMF. Even up-to date solid-phase synthesis requires solvent. What's more, they have other drawbacks including long reaction time, producing much wastes and by-products, tedious experimental procedure.     

A Facile Synthesis of 5-(2′-Oxoalkyl)-2-Cyclopenten-1-Ones

In spite of the fact that a number of methods are available for the preparation of C-5-monoalkylated (simple alkyl) cyclopentenones¹, general synthetic routes leading to cyclopentenones possessing an activated side chain at C-5 remain virtually unknown². In connection with our synthetic studies on iridoids³, we have developed a convenient synthesis of the title compounds which we wish to report herein.     

Facile Synthesis of 1‐Aryl‐2‐propanones from Aromatic Amine

A facile synthesis of aryl propanones using aromatic amines as precursors, via an improved Meerwein arylation reaction under mild conditions, is reported.     

A Facile Synthesis of 0,0-Dialkyl-α-(Phenyl Carbamyloxy) Alkyl Phosphonates

TheC-ph0sphorylatedcarbamatederivativeshavereceivedspecialattentionbecauseoftheirpesticidalactivity.Wewereinterestedinfindingafacilemethodf0rthesynthesis0fthetitlec0mpounds.Therehavebeens0mereportsonthesynthesis0f(dialkylph0sphono)arylmethylcarbamates',whichwerepreparedbytreatingdialkylis0cyanat0phosphitewithsubstitutedbenzaldehydefoll0wedbyhydr0lysiswithwater.However,thismeth0dhassomelimitationsduetol0wyield,anddialkylisocyanatophosphiteisnoteasytoprepare.Inthestudy0fthenucIeophilicadditionr…     

Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C−O Bond Formation

A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C−O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.     

A Facile and Efficient Synthesis of N,N—Dimethylarylamines from Aryl Bromides

Catalytie amination of aryl bromides with in situ generated dimethylamines from N,N-dimethylacetamide(DMA)has been suceessfully carried out using Ni(phen)Cl2 as catalyst,Both electron-rich and electron-poor aromatie system reaeted smoothly under the conditions to give N,N-dimethylarylamines in good yields.     

One Step of Palladium Catalyzed Benzodioxane Ring C–O Bond Formation,Synthesis of Isoamericanol A and Isoamericanin A

Abstract

A number of benzodioxane compounds were synthesized using the palladium‐catalyzed etherification of aryl halides by employing triphenylphosphane ligands. This method was used as key step in the synthesis of two natural products isoamericanol A and isoamericanin A.     

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.     

C‐C Bond Formation by Radical Cyclization: Regioselective Synthesis of [6,6] Pyrano pyran System

Abstract

Abstract:?A number of 4‐aryloxymethyl pyrano[3,2‐c][1]benzopyran‐5‐(2H)‐ones 3(a–f) were prepared by refluxing 4‐chloromethyl pyrano[3,2‐c][1]benzopyran‐5‐(2H)‐ones 1(a,b) with o‐bromophenols 2(a–c) in acetone in the presence of anhydrous potassium carbonate and sodium iodide in 70–80% yield. Compounds 3(a–f) were then subjected to radical cyclization by refluxing with tri‐n‐butyltin chloride, sodium cyanoborohydride, and azobisisobutyronitrile (AIBN) in dry benzene for 4–5 h to give a cis‐diastereomeric mixture of [6,6]pyranopyran derivatives in 80–85% yield.     

A Facile Synthesis of (±)2-(4-Chlorophenyl)-α-Methyl-5-Benzoxazoleacetic Acid (Benoxaprofen)

A convenient four step procedure for the synthesis of benoxaprofen is described starting with 4-hydroxyphenylacetic acid.     

L ‐Proline‐Promoted CuI‐Catalyzed C‐S Bond Formation between Aryl Iodides and Thiols

An improved, mild procedure for the CuI‐catalyzed coupling reactions of aryl iodides with aliphatic and aromatic thiols, using L ‐proline as the ligand, is reported. This procedure is noteworthy given its high generality and exceptional level of functional group toleration.     

A New Synthesis of 1-(ω-Haloalkyl)-Imidazoles

Inconnechonwith0urreeenteffortStowardsthesynthesis0fartificialreceptorsandenzymescontalninginddazoles",itwasnecessarytoprepareaclassofl-(orhaloalkyl)-inddazolesassyntheticpreeursors.The0nlyreportinliteratureislindtedforthepreparationofl-(2-bromoethyl)inddazolebyreactingimidazolefirstwithethylenecarbonate,thenwiththionylbr0nddet0givea24.5%yield'.Therearenogeneralpreparativemethodsforthesecompounds.RecenUy,HorvathreportedasimPlemethodf0rthepreparationofl-substitutedinddazolesfromaHoffmann-type…     

A Facile Synthesis of an Advanced Glycosylation Endproduct 2-(2′-furoyl)-4(5)-(2′-furanyl)-1H-imidazole

Abstract: A three step synthesis of the advanced glycosylation endproduct 2-(2′-furoyl)-4(5)-(2′-furanyl)-1H-imidazole (4, FFI) has been achieved from 2-acetylfuran. The key step in the synthesis was the rearrangement of the hydrazinium bromide 3 in refluxing methanol.     

An S=1 Iron(IV) Intermediate Revealed in a Non-Heme Iron Enzyme-Catalyzed Oxidative C−S Bond Formation

Ergothioneine (ESH) and ovothiol A (OSHA) are two natural thiol-histidine derivatives. ESH has been implicated as a longevity vitamin and OSHA inhibits the proliferation of hepatocarcinoma. The key biosynthetic step of ESH and OSHA in the aerobic pathways is the O₂-dependent C−S bond formation catalyzed by non-heme iron enzymes (e.g., OvoA in ovothiol biosynthesis), but due to the lack of identification of key reactive intermediate the mechanism of this novel reaction is unresolved. In this study, we report the identification and characterization of a kinetically competent S=1 iron(IV) intermediate supported by a four-histidine ligand environment (three from the protein residues and one from the substrate) in enabling C−S bond formation in OvoA from Methyloversatilis thermotoleran, which represents the first experimentally observed intermediate spin iron(IV) species in non-heme iron enzymes. Results reported in this study thus set the stage to further dissect the mechanism of enzymatic oxidative C−S bond formation in the OSHA biosynthesis pathway. They also afford new opportunities to study the structure-function relationship of high-valent iron intermediates supported by a histidine rich ligand environment.     

Facile Synthesis of (S,S)‐1,2‐Diacylamides and (S,S)‐1,2‐Diamines with C 2‐Symmetry

A series of chiral vicinal tertiary diacylamides with C ₂‐symmetry was synthesized from (S)‐α‐phenylethylamine, different aromatic aldehydes, and oxalyl chloride. The diacylamides obtained were then reduced to afford chiral vicinal diamines with C ₂‐symmetry. We propose that the diacylamides existed in four stable conformational isomers in solution because of the dihedral angle between acylamide bonds.     

Concise Synthesis of α-(Hydroxymethyl) Alkyl and Aryl Vinyl Ketones

2,4-Diketoesters 2 have first been reported as starting materials for the synthesis of a new class of α-hydroxymethyl-α,β-unsaturated ketones 3. Thus, under heterogeneous liquid–liquid medium in the presence of concentrated aqueous potassium carbonate as a base, both aliphatic and aromatic 2,4-dioxoalkanoates 2 react with aqueous formaldehyde to afford the corresponding ketones 3 in fair to good yields.     

A Facile Stereospecific Synthesis of 1, 3-Enynylsulfides via Sonogashira Coupling of (E)-α-Iodovinyl Sulfides with 1-Alkynes

The discovery of strong antifungal agents1 and new powerful antitumor antibiotics2 has stimulated intense interest in the chemistry of enynes3, which is at the origin of the biological properties of these substances. The conjugated enynes are also the imp…     

A Facile Synthesis of Some Substituted1，2┐Naphthoquinones

从１－四氢萘醌合成１，２－萘醌的关键反应是利用二氧化硒氧化，其特点是在一步过程中引入羰基和双键。经过八步反应合成了５，７－二甲氧基－３，４－萘醌－２－甲酸甲酯及其８－溴衍生物；后者经还原为萘二酚，并对其进行氧化双偶合反应，但未获得成功，并为之作了解释