A Palladium-Catalyzed Method for the Synthesis of 2-(α-Styryl)-2,3-dihydroquinazolin-4-ones and 3-(α-Styryl)-3,4-dihydro-1,2,4-benzothiadiazine-1,1-dioxide: Access to 2-(α-Styryl)quinazolin-4(3H)-ones and 3-(α-Styryl)-1,2,4-benzothiadiazine-1,1-dioxides

A solvent controlled regioselective synthesis of 2- and 4-substituted α-carbolines under palladium catalysis

A facile method for the chemodivergent synthesis of α-carbolines 1via palladium catalyzed [3+3] annulations of tosyliminoindolines 6 with α, β-unsaturated aldehydes 7 is described. Mechanistically, this cascade reaction proceeds through either a carba-Michael (in DMF) or aza-Michael (in NMA) pathway followed by intramolecular cyclization of the intermediate. A preliminary photo-physical study on selected products is also reported.

p-Toluenesulfonic acid-promoted organic transformations for the generation of molecular complexity

Since the beginning of this century, p-toluenesulfonic acid (p-TSA) catalysed organic transformations have been an active area of research for developing efficient synthetic methodologies. Often, catalysis using p-TSA is associated with many advantages, such as operational simplicity, high selectivity, excellent yields, and ease of product isolation, which make organic synthesis convenient and versatile. Notably, p-TSA is a non-toxic, commercially available, inexpensive solid organic compound that is soluble in water, alcohols, and other polar organic solvents. p-TSA is a strong acid compared to many protic or mineral acids and its high acidity helps activate different organic functional groups. p-TSA-promoted conversions are fast, have a high atom and pot economy, and feature a multiple bond-forming index. Therefore, the utilization of p-TSA enables the synthesis of many important structural scaffolds without any hazardous metals, making it desirable in numerous applications of sustainable and green chemistry. Recently, this emerging area of research has become one of the pillars of synthetic organic chemistry to synthesise biologically relevant, complex carbocycles and heterocycles. This study provides a comprehensive summary of methods, applications, and mechanistic insights into p-TSA-catalysed organic transformations, covering the literature reports that have appeared since 2012.

Crystal structure and Hirshfeld surface analysis of 3-methyl-4-oxo-N-phenyl-3,4-di-hydro-quinazoline-2-carbo-thio-amide

The asymmetric unit of the title compound, C16H13N3OS, comprises two mol-ecules (A and B) with similar conformations that differ mainly in the orientation of the phenyl group relative to the rest of the mol-ecule, as expressed by the Cthio-amide-Nthio-amide-Cphen-yl-Cphen-yl torsion angle of 49.3 (3)° for mol-ecule A and of 5.4 (3)° for mol-ecule B. In the crystal, two inter-molecular N-H⋯N hydrogen bonds lead to the formation of a dimer with R 2 2(10) graph-set notation. A Hirshfeld surface analysis revealed that H⋯H inter-actions are the most important inter-molecular inter-actions, contributing 40.9% to the Hirshfeld surface.

Palladium-Catalyzed Synthesis of 1-Vinyltetrahydro-β-carbolines and Aza-spiroindolenines: Access to the Syntheses of 1-Vinyl-β-carbolines and Eudistomins Y1 and Y2

A general synthesis of 1-vinyltetrahydro-β-carbolines (THBCs) has been achieved via palladium(0)-catalyzed cyclocondensation between allenyltryptamines and aryl iodides. Aza-spiroindolenines could also be accessed from the N-unsubstituted indole substrates by simply tweaking the reaction conditions. DDQ-mediated oxidation of THBCs easily afforded β-carbolines, which could be synthetically transformed into 1-aroyl-β-carbolines of pharmacological interest. Formal total syntheses of eudistomins Y1 and Y2 have also been achieved.

Palladium(ii) catalysed cascade strategy for the synthesis of dibenzo[5,6:7,8]cycloocta[1,2-b]indol-10-ols/-10(15H)-ones: easy access to 1,3,5,7-cyclooctatetraenes (COTs)

An atom-economic Pd(ii)-catalysed cascade cyclisation of 2-(biphenylethynyl)anilines tethered to an aldehyde or cyano group leads to the formation of dibenzo[5,6:7,8]cycloocta[1,2-b]indol-10-ols 6 or dibenzo[5,6:7,8]cycloocta[1,2-b]indol-10(15H)-ones 8 with high yields (up to 95%). The reaction proceeds via amino-palladation of the alkyne followed by nucleophilic addition onto the aldehyde/cyano group. Treatment of 6 with p-TsOH·H₂O smoothly provided cyclooctatetraene (COT) derivatives 7.

Microwave-assisted synthesis of quinazolin-4(3H)-ones catalyzed by SbCl3

Antimony(III) trichloride (SbCl3) is an effective catalyst (1 mol%) for the condensation of anthranilic amide with various aldehydes or ketones to quinazolin-4(3H)-one derivatives in good to excellent yields under microwave irradiation. The process is carried out within several minutes under solvent-free conditions. This general methodology has the advantages of simplicity, mild reaction conditions and high yields of products.

Synthesis of novel 1,2,4-thiadiazinane 1,1-dioxides via three component SuFEx type reaction

Herein, we report the preparation of 1,2,4-thiadiazinane 1,1-dioxides from reaction of β-aminoethane sulfonamides with dichloromethane, dibromomethane and formaldehyde as methylene donors. The β-aminoethane sulfonamides were obtained through sequential Michael addition of amines to α,β-unsaturated ethenesulfonyl fluorides followed by further DBU mediated sulfur(vi) fluoride exchange (SuFEx) reaction with amines at the S-F bond.

Oxone-mediated annulation of 2-aminobenzamides and 1,2-diaminobenzenes withsec-aminesviaimine-N-oxides: new syntheses of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles by reaction of imine-N-oxides with 2-aminobenzamides and 1,2-diaminobenzenes is described.

Interception of amide ylides with sulfonamides: synthesis of (E)-N-sulfonyl amidines catalyzed by Zn(OTf)2

Through the interception of amide ylides with sulfonamides, we herein report an intermolecular condensation reaction between sulfonamides and common amides.