IMDAV reaction between phenylmaleic anhydride and thienyl(furyl)allylamines: Synthesis and molecular structure of (3a SR,4 RS,4a RS,7a SR)-5-oxothieno- and (3a SR,4 SR,4a RS,7a SR)-5-oxofuro[2,3- f ]isoindole-4-carboxylic acids

The title compounds C 24 H 21 NO 3 S, I, and C 24 H 21 NO 4, II, are the products of the IMDAV reaction between phenylmaleic anhydride and thienyl(furyl)allylamines. Their molecular structures comprise fused tricyclic systems containing thiophene, cyclohexene and pyrrolidine rings (I) or furan, cyclohexene and pyrrolidine rings (II). The central cyclohexene and pyrrolidine rings in both compounds adopt slightly twisted boat and envelope conformations, respectively. The dihedral angles between the basal plane of the pyrrolidine ring and the thiophene (in I) or furan (in II) ring plane are 22.74 (16) and 26.29 (5)°, respectively. The nitrogen atom both in I and II has practically planar environment [the sums of the bond angles are 359.8 and 358.9°, respectively]. In the crystal of I, the molecules form hydrogen-bonded zigzag chains along [010] through strong intermolecular O - H⋯O hydrogen bonds involving carboxylic and keto groups, whereas in the crystal of II, the molecules are joined into centrosymmetric dimers by strong O - H⋯O hydrogen bonds between the carboxylic groups. In II, the atoms involved into these hydrogen bonds (and hence the whole carboxylic group) are disordered over two sets of sites with an occupancy ratio of 0.6:0.4. Compounds I and II crystallize as racemates consisting of enantiomeric pairs of the 3aSR,4RS,4aRS,7aSR and 3aSR,4SR,4aRS,7aSR diastereomers, respectively. © © Toze et al. 2018

Continuous-flow catalytic hydrogenation of 3a,6-epoxyisoindoles

Selective catalytic (10% Pd/C) hydrogenation of the double bond in the oxabicyclo[2.2.1]heptene fragment of substituted fused 1-oxo-3a,6-epoxyisoindoles is described. A continuous-flow hydrogenation device that incorporates in situ hydrogen generation by electrolysis of water was used. Changing the hydrogen source from water to deuterium oxide provides possibility to synthesize deuterated oxoepoxyisoindolones. Hydrogenation is stereoselective to give exclusively exo-cis deuterated derivatives. © 2015 Springer Science+Business Media, Inc

Continuous-flow catalytic hydrogenation of 3a,6-epoxyisoindoles

Selective catalytic (10% Pd/C) hydrogenation of the double bond in the oxabicyclo[2.2.1]heptene fragment of substituted fused 1-oxo-3a,6-epoxyisoindoles is described. A continuous-flow hydrogenation device that incorporates in situ hydrogen generation by electrolysis of water was used. Changing the hydrogen source from water to deuterium oxide provides possibility to synthesize deuterated oxoepoxyisoindolones. Hydrogenation is stereoselective to give exclusively exo-cis deuterated derivatives. © 2015 Springer Science+Business Media, Inc

[3+2] Cycloaddition of o-nitrophenyl azide to 3a,6-epoxyisoindoles

[3+2] Cycloaddition of o-nitrophenyl azide to the multiple bond of oxabicyclo[2.2.1]heptene moiety in substituted 3a,6-epoxyisoindoles was performed. The 1,3-dipolar addition reaction proceeded stereoselectively, producing a pair of isomeric cis-4,8a-epoxy[1,2,3]triazolo[4,5-e]isoindoles. This approach demonstrated synthetic access to isomeric epoxy-1,2,3-benzotriazoles fused with a γ-butyrolactam moiety. © 2018, Springer Science+Business Media, LLC, part of Springer Nature

Wagner–Meerwein rearrangement in 2,6a-epoxyoxireno[e]isoindole series

[Figure not available: see fulltext.] A cation-catalyzed Wagner–Meerwein skeletal rearrangement in octahydro-2,6a-epoxyoxireno[e]isoindole series was studied. It was shown that the reaction proceeds ambiguously when effected by boron trifluoride etherate in acetic anhydride: the target 4,5-bis(acetoxy)-4,6-epoxycyclopenta[c]pyridines as well as the products of their further degradation, cyclopenta[c]pyridines, were isolated from the reaction mixture in 10–15% yields as single diastereomers. © 2016, Springer Science+Business Media New York

Iodine Acetate as a Mild Selective Agent for the Wagner–Meerwein Rearrangement in 3a,6-Epoxyisoindoles

[Figure not available: see fulltext.] The iodine-initiated cationic skeletal Wagner–Meerwein rearrangement in tetrahydro-3a,6-epoxyisoindol-1-ones has been studied. It was shown that by the action of iodine acetate in acetic anhydride the reaction proceeds regio- and stereoselectively with the formation of 5-iodo-4,6-epoxycyclopenta[c]pyridin-4-yl acetates. The proposed reagent provides better yields of rearrangement products than those described in the literature. © 2020, Springer Science+Business Media, LLC, part of Springer Nature

Wagner–Meerwein rearrangement in 2,6a-epoxyoxireno[e]isoindole series

[Figure not available: see fulltext.] A cation-catalyzed Wagner–Meerwein skeletal rearrangement in octahydro-2,6a-epoxyoxireno[e]isoindole series was studied. It was shown that the reaction proceeds ambiguously when effected by boron trifluoride etherate in acetic anhydride: the target 4,5-bis(acetoxy)-4,6-epoxycyclopenta[c]pyridines as well as the products of their further degradation, cyclopenta[c]pyridines, were isolated from the reaction mixture in 10–15% yields as single diastereomers. © 2016, Springer Science+Business Media New York