Application of the intramolecular Diels-Alder vinylarene (IMDAV) reaction for the synthesis of benzo-, carbocyclo-, thienothiopheneisoindolecarboxylic acids and its limitations.

Thienylallylamines, readily accessible from the corresponding thienyl aldehydes, react with maleic and trifluoromethylmaleic anhydrides leading to the formation of acids with a thieno[2,3-]isoindole core. The reaction sequence involves two successive steps: acylation of the nitrogen atom of the initial allylamine and the intramolecular Diels-Alder vinylarene (IMDAV) reaction. The scope and limitations of the proposed method were thoroughly investigated.

One-Pot Reaction Sequence: -Acylation/Pictet-Spengler Reaction/Intramolecular [4 + 2] Cycloaddition/Aromatization in the Synthesis of β-Carboline Alkaloid Analogues.

One-pot synthesis of tetrahydro-β-carbolines, fused with an isoindole core, was proposed starting from maleic anhydride and azomethines easily available from tryptamines and 3-(hetaryl)acroleins. This sequence includes four key steps: an acylation of the aldimine with maleic anhydride, a Pictet-Spengler cyclization, an intramolecular Diels-Alder reaction, and a concluding [1,3]- shift. As a result, six- or seven-nuclear alkaloid-like heterocyclic systems, containing a benzo[1,2]indolizino[8,7-]indole fragment annulated with furan, thiophene, or pyrrole, are formed in a diastereoselective manner.

Domino Three-Component -Acylation/[4 + 2] Cycloaddition/Alder-ene Synthesis of Polysubstituted Benzo[]isoindole-4-carboxylic Acids.

Diversely substituted, partially saturated benzo[]isoindole-4-carboxylic acids were synthesized by a new three-component reaction (3CR) starting from cinnamic amines (3-arylallylamines), maleimides, and maleic anhydride. The process consists of -acylation of the amines by maleic anhydride, intramolecular [4 + 2] cycloaddition in vinylarenes (the IMDAV reaction), and the concluding Alder-ene reaction between Diels-Alder intermediates and maleimides. All of the reaction steps proceed in a highly regio- and stereoselective manner, furnishing five adjacent chiral centers and leading to a single diastereoisomer of the title compound.

Crystal structure and Hirshfeld surface analysis of 2-benzyl-4,5-di-bromo-2,3,3a,4,5,6,7,7a-octa-hydro-3a,6-ep-oxy-1-isoindol-1-one.

The title compound, CHBrNO, crystallizes with two mol-ecules in the asymmetric unit of the unit cell. In both mol-ecules, the tetra-hydro-furan rings adopt an envelope conformation with the O atom as the flap and the pyrrolidine rings adopt an envelope conformation. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming sheets lying parallel to the (002) plane.

Crystal structure and Hirshfeld surface analysis of ethyl (4,4a)-2-methyl-5,8-dioxo-6-phenyl-4a,5,6,7,7a,8-hexa-hydro-4-furo[2,3-]iso-indole-4-carboxyl-ate.

In the title compound, CHNO, the central six-membered ring has a slightly distorted half-chair conformation, with puckering parameters of = 0.3387 (11) Å, θ = 49.11 (19)° and φ = 167.

Raise the anchor! Synthesis, X-ray and NMR characterization of 1,3,5-triazinanes with an axial tert-butyl group.

N-t-Bu-N',N''-Disulfonamide-1,3,5-triazinanes were synthesized and characterized by X-ray single crystal structure analysis. In the course of the X-ray structure elucidation, the first solid experimental evidence of the axial position of the tert-butyl group in unconstrained hexahydro-1,3,5-triazacyclohexanes was obtained. Dynamic low-temperature NMR analysis allowed to fully investigate a rare case of crystallization-driven unanchoring of the tert-butyl group in the chair conformation of saturated six-membered cycles.

Three-component reaction between isatoic anhydride, amine and meth-yl-subs-tituted furyl-acryl-alde-hydes: crystal structures of 3-benzyl-2-[()-2-(5-methylfuran-2-yl)vin-yl]-2,3-di-hydro-quinazolin-4(1)-one, 3-benzyl-2-[()-2-(furan-2-yl)-1-methyl-vin-yl]-2,3-di-hydro-quinazolin-4(1)-one and 3-(furan-2-ylmeth-yl)-2-[()-2-(furan-2-yl)-1-methyl-vin-yl]-2,3-di-hydro-quinazolin-4(1)-one.

Compounds (I), CHNO, (II), CHNO and (III), CHNO are the products of three-component reactions between isatoic anhydride, the corresponding amine and 3-(5-methylfuran-2-yl)- or (furan-2-yl)-2-methyl-acryl-aldehyde. Compound (I) crystallizes in the monoclinic space group 2/, while compounds (II) and (III) are isostructural and crystallize in the ortho-rhom-bic space group . The tetra-hydro-pyrimidine ring in (I)-(III) adopts a conformation.

Crystal structure of 3-benzyl-2-[()-2-(furan-2-yl)ethen-yl]-2,3-di-hydro-quinazolin-4(1)-one and 3-benzyl-2-[()-2-(thio-phen-2-yl)ethen-yl]-2,3-di-hydro-quinazolin-4(1)-one from synchrotron X-ray diffraction.

The chiral title compounds, CHNO, (I), and CHNOS, (II) - products of the three-component reaction between benzyl-amine, isatoic anhydride and furyl- or thienyl-acrolein - are isostructural and form isomorphous racemic crystals. The tetra-hydro-pyrimidine ring in (I) and (II) adopts a sofa conformation. The amino N atom has a trigonal-pyramidal geometry [sum of the bond angles is 347.

Diels-Alder reactions between hexafluoro-2-butyne and bis-furyl dienes: kinetic versus thermodynamic control.

The tandem [4+2] cycloaddition between hexafluoro-2-butyne and bis-furyl dienes, like difurfuryl ester, at room temperature leads to the kinetically controlled "pincer"-adducts - annulated 4a,8a-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes. On the other hand, if these reactions proceed at 140 °C, only the thermodynamically controlled "domino"-adducts - annulated 2,3-bis(trifluoromethyl)hexahydro-1,4:5,8-diepoxynaphthalenes - are formed. Therefore, a very rare and unexpected example of full kinetic and thermodynamic control in the Diels-Alder reaction is reported in this paper.

Inter-action between maleic acid and --furfuryl-amines: crystal structure of 2-methyl--[(5-phenyl-furan-2-yl)meth-yl]propan-2-aminium (2)-3-carb-oxy-acrylate and -[(5-iodo-furan-2-yl)meth-yl]-2-methyl-propan-2-aminium (2)-3-carb-oxy-prop-2-enoate.

The title mol-ecular salts, CHNO·CHO, (I), and CHINO·CHO, (II), have very similar mol-ecular geometries for both cation and anion. The anions of both (I) and (II) are practically planar (r.m.

Crystal strucutre of rac-methyl (11aR*,12S*,13R*,15aS*,15bS*)-11-oxo-11,11a,12,13-tetra-hydro-9H,15bH-13,15a-ep-oxy-isoindolo[1,2-c]pyrrolo[1,2-a][1,4]benzodiazepine-12-carboxyl-ate.

The title compound, C21H18N2O4, obtained as a racemate, contains a novel heterocyclic system, viz. isoindolo[1,2-c]pyrrolo-[1,2-a][1,4]benzodiazepine. The central diazepane ring has a distorted boat conformation with two phenyl-ene-fused and one methine C atom deviating by 0.

rac-Methyl (3aR*,4S*,5R*,7aR*)-5,7a-bis-(acet-yloxy)-3-oxo-2-phenyl-octa-hydro-1H-iso-indole-4-carboxyl-ate.

The title molecule, C20H23NO7, the product of nucleophilic cleavage of the 3a,6-ep-oxy bridge in 1-oxo-2-phenyl-octa-hydro-3a,6-ep-oxy-iso-indole-7-carboxyl-ate, comprises a cis-fused bicyclic system containing a 2-pyrrolidinone ring in an envelope conformation (with the C atom bearing the carboxyl-ate substituent as the flap) and a cyclo-hexane ring in a chair conformation. The carboxyl-ate substituent occupies the equatorial position, whereas the two acet-yloxy substituents are in axial positions. The N atom has a trigonal-planar geometry, the sum of the bond angles being 359.

2-Benzazepine nitrones protect dopaminergic neurons against 6-hydroxydopamine-induced oxidative toxicity.

A number of C-3 spirocyclic 2-benzazepine analogs of α-phenyl-N-tert-butyl nitrone (PBN) were synthesized and tested for their activity in protecting rat brain mitochondria and dopaminergic (DA) neurons against 6-hydroxydopamine (6-OHDA), a toxin inducing destruction of the DA nigro-striatal pathway in rodent models of Parkinson's disease. The newly synthesized nitrone derivatives were firstly investigated for their activity in decreasing the level of hydroxyl radicals generated during 6-OHDA oxidation, and inhibit lipid peroxidation (TBARS assay) and protein carbonyl content (PCC) in rat brain mitochondria. Most of the studied 2-benzazepine nitrones showed inhibitory potencies in both TBARS and PCC assays at least two magnitude orders higher than that of PBN.

(6aS*,6bS*,11R*,11aR*)-6-(2-Furyl-methyl)-5,12-dioxo-5,6,6a,6b,7,11,11a,12-octa-hydro-furo[3',2':5,6]isoindolo[2,1-a]quinazoline-11-carb-oxy-lic acid.

The title compound, C(23)H(18)N(2)O(6), is the product of an intra-molecular thermal cyclo-addition within 1-malein-2-[(E)-2-(2-fur-yl)vin-yl]-4-oxo-3,4-dihydro-quinazoline. The mol-ecule comprises a previously unknown fused penta-cyclic system containing two five-membered rings (2-pyrrolidinone and furan) and three six-membered rings (benzene, 2,3-dihydro-4-pyrimidinone and dihydro-cyclo-hexa-ne). The central five-membered pyrrolidinone ring has the usual envelope conformation.

Methyl 7,8-diacet-oxy-11-oxo-5-(2-oxo-pyrrolidin-1-yl)-7,9-epoxy-cyclo-penta-[4,5]pyrido[1,2-a]quinoline-10-carboxyl-ate sesquihydrate.

The title compound, C(26)H(28)N(2)O(9)·1.5H(2)O, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as a sesquihydrate with the O atom of one of the two independent water mol-ecules occupying a special position on a twofold axis. The organic mol-ecule comprises a fused penta-cyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) and three six-membered rings (piperidinone, tetra-hydro-pyridine and benzene).

Methyl 4,5-diacet-oxy-1-oxo-2-phenyl-perhydro-4,6-epoxy-cyclo-penta-[c]pyridine-7-carboxyl-ate ethanol solvate.

The title compound, the product of an acid-catalysed Wagner-Meerwein skeletal rearrangement, crystallizes as an ethanol monosolvate, C(20)H(21)NO(8)·C(2)H(6)O. The title mol-ecule comprises a fused tricyclic system containing two five-membered rings (cyclo-pentane and tetra-hydro-furan) in the usual envelope conformations and one six-membered ring (piperidinone) adopting a flattened twist-boat conformation.