A cascade process toward the synthesis of fused polycyclic dihydropyridines

Efficient synthesis of isoindolones by intramolecular cyclisation of pyridinylbenzoic acids

A straightforward one-pot method for the synthesis of unreported pyrido-[2,1-a]isoindolones in excellent yield is described. Two novel isoindolones were synthesized and fully characterized. The alkyl substituents on the pyridine play an important role in the outcome of the reaction. The mechanism, investigated through DFT calculations, features an unprecendented intramolecular cyclization reaction involving a carboxylic acid activated by tosyl chloride and an electron-poor pyridinic nitrogen. This protocol completes the known strategies to obtain functionalized isoindolones.

Synthesis of dihydroisoindolo[2,1-a]quinolin-11-ones, their in silico ADMET properties and in vitro antitumor activities

We evaluated the antitumoral activity of diverse series of 5-aryl-dihydroisoindolo[2,1-a]quinolin-11-ones, AIIQ (Aryl IsoIndolo-Quinoline, 4a-m), and 5-vinyl dihydroisoindolo[2,1-a]quinolin-11-ones, VIIQ (Vinyl IsoIndolo-Quinoline, 6a-l), obtained using three component imino Diels-Alder (DA) reaction of anilines, o-phthalaldehyde and dienophiles. The first series was obtained in previous work employing isoeugenol and anethole as dienophiles, whereas the vinyl series was synthesized in high yields (75-90%) using isoprene as a dienophile. The cytotoxic activity of both AIIQ and VIIQ series was evaluated against four cancer lines, identifying a new lead compound 4h from the AIIQ series, active against MCF-7 (310 nM), SKBR3 (1434 nM), PC3 (210 nM) and HeLa (79 nM) cells with high selectivity. In addition, in silico ADMET properties for the two series were assessed and discussed.

Synthesis and solid-state fluorescence properties of pentacyclic 7-substituted-indeno[1′,2′:4,5]pyrido[2,1-a]isoindol-5-ones

New pentacyclic indeno[1′,2′:4,5]pyrido[2,1-a]isoindol-5-ones were designed which possess quantum yields in the solid state up to 32%. The importance of the substituent in 7-position was highlighted through crystal packing analysis.

Aza-Diels-Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

The synthesis of 5-substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones via [4 + 2] imino-Diels-Alder cyclization from N-aryl-3-hydroxyisoindolinones and N-vinyl lactams under Lewis acid-catalysed anhydrous conditions is reported. Reactions of N-(2-substituted-aryl)-3-hydroxyisoindolinones with N-vinylpyrrolidone under identical conditions resulted in the formation of 2-(2-substitued-aryl)-3-(2-(2-oxopyrrolidin-1-yl)vinyl)isoindolin-1-one analogues indicating steric hinderance as the cause of deviation. The probable mechanism of the reaction based on the results from X-ray crystallography and molecular modelling is discussed.

Skeletal diverse synthesis of N-fused polycyclic heterocycles via the sequence of Ugi-type MCR and CuI-catalyzed coupling/tandem Pictet-Spengler reaction

Several diversity-oriented syntheses of N-fused polycyclic heterocycles have been demonstrated but most of them are based on point diversity within the same library and usually involve time-consuming sequential multistep syntheses, which also suffer from low yields and/or poor precursor scopes. We have developed a new strategy for the syntheses of skeletal diverse N-fused polycyclic compounds via an Ugi-type MCR followed by a CuI-catalyzed coupling reaction or tandem Pictet-Spengler reaction. This two-step sequence provides eight distinct skeleton of fused {6-5-5-6}, {5-5-5-6}, {6-5-6-6}, and {5-5-6-6} ring systems that have applications in medicinal chemistry and chemical genetics too.

The methyl group as a source of structural diversity in heterocyclic chemistry: side chain functionalization of picolines and related heterocycles

The reaction of 2-picoline at the methyl group with NDA and KDA followed by dimethyldisulfide trapping furnished, respectively, dithioacetals and trithioortho esters with high selectivity. The method was successfully applied to other methyl-substituted pyridines, quinolines, and pyrazines. Dithioketals were prepared by a one-pot procedure involving the reaction of metalated 2-picoline with 2 equiv of dimethyldisulfide followed by in situ trapping with a second electrophile. All of the generated thio-substituted compounds were efficiently transformed in presence of mercury salts or under oxidizing conditions to other functional groups comprising aldehydes, ketones, ketals, thiol esters, orthoesters, and esters.