5-Aryl-2-furaldehydes in the synthesis of tetrahydropyrimidinones by Biginelli reaction

5-Aryl-2-furaldehydes, obtained by furfural arylation with arenediazonium salts, react with ethyl acetoacetate or acetylacetone and (thio)- urea in the presence of FeCl3·6H2O as a catalyst. A series of ethyl 4-(5-aryl-2-furyl)-6-methyl-2-oxo(thioxo)-1,2,3,4-tetrahydropyrimidine- 5-carboxylates was obtained. © 2018 Springer Science+Business Media, LLC

5-Aryl-2-furaldehydes in the synthesis of tetrahydropyrimidinones by Biginelli reaction

5-Aryl-2-furaldehydes, obtained by furfural arylation with arenediazonium salts, react with ethyl acetoacetate or acetylacetone and (thio)- urea in the presence of FeCl3·6H2O as a catalyst. A series of ethyl 4-(5-aryl-2-furyl)-6-methyl-2-oxo(thioxo)-1,2,3,4-tetrahydropyrimidine- 5-carboxylates was obtained. © 2018 Springer Science+Business Media, LLC

(4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a, 8-hexahydro-4H-furo[2,3-f]isoindole-4-carboxylic acid

The asymmetric unit of the title compound, C17H 15NO4, contains two independent molecules with similar geometric parameters. In both molecules, the conformation of the cyclohexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the -pyrrolidinone ring as the flap. In the crystal, O - H⋯O hydrogen bonds between the carboxylic and carbonyl groups link alternate independent molecules into chains propagating in the b-axis direction. The crystal packing also features weak C - H⋯π interactions

(4R*,4aR*,7aS*)-5-Oxo-6-phenyl-4a,5,6,7,7a, 8-hexahydro-4H-furo[2,3-f]isoindole-4-carboxylic acid

The asymmetric unit of the title compound, C17H 15NO4, contains two independent molecules with similar geometric parameters. In both molecules, the conformation of the cyclohexene ring is half-chair, while the pyrrolidinone ring adopts an envelope conformation with the γ-carbon atom of the -pyrrolidinone ring as the flap. In the crystal, O - H⋯O hydrogen bonds between the carboxylic and carbonyl groups link alternate independent molecules into chains propagating in the b-axis direction. The crystal packing also features weak C - H⋯π interactions

Synthesis of epoxyisoindolo[1,2-a]isoquinolinium salts by an intramolecular [2+4] cycloaddition reaction in 2-allyl-1-furylisoquinolinium halides

We examined the tandem alkylation/[2+4] cycloaddition of 1-(2-furyl)-3,4-dihydroisoquinolines by various allyl halides. It was found that the process occurred through the intermediate formation of 2-allyl-1-furyl-3,4- dihydroisoquinolinium salts with a subsequent intramolecular exo addition of the allyl fragment to the furan ring. The adducts obtained were structural analogs of the isoindolo-[1,2-a]isoquinoline alkaloids jamtine and hirsutine. © 2013 Springer Science+Business Media New York

The intramolecular Diels-Alder vinylthiophen (IMDAV) reaction: An easy approach to thieno[2,3-f]isoindole-4-carboxylic acids

The reaction of readily accessible 3-(thien-2-yl)allylamines with maleic anhydride, followed by a domino sequence involving successive acylation/[4+2] cycloaddition steps, leads to the formation of the thieno[2,3-f]isoindole core. The key step, the intramolecular Diels-Alder vinylaren (IMDAV) reaction, proceeds with high level of diastereoselectivity and with formation of a single diastereoisomer of the target product 4,4a,5,6,7,7a-hexahydro-3aH-thieno[2,3-f]isoindole-4-carboxylic acids in excellent yields. If the reaction is carried out at room temperature, it occurs in 2–3 days and the proton migration (H-shift) does not take place at the last stage. In boiling benzene, the reaction is complete after three hours, but in this case a slight impurity of byproducts bearing aromatic thiophene ring – 4a,5,6,7,7a,8-hexahydro-4H-thieno[2,3-f]isoindole-4-carboxylic acids is formed. © 2017 Elsevier Lt