Synthesis of spiro[bicyclo[2.2.1]heptane-2,2′-furan]-3-amines via stereoselective cycloadditions of trimethylenemethane to (1S,3EZ,4R)-3-arylimino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones

Stereoselective [3+2] cycloadditions of trimethylenemethane (TMM) to the exocyclic CO and CN double bonds of (1S,3EZ,4R)-3-arylimino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones gave the corresponding spiro[bicyclo[2.2.1]heptane-2,2′-furan] and spiro[bicyclo[2.2.1]heptane-3,2′-pyrrolidine] derivatives. Further stereoselective reductions of the CN or CO bond in these cycloadducts furnished new chiral amines, diamines, and a new aminoalcohol. All cycloadditions and reductions of the CN double bonds took place from the less hindered endo-face of the (1S,3EZ,4R)-3-arylimino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones, exclusively, thus giving the corresponding products in 100% de. The structures were determined by NMR, NOESY spectroscopy, and by X-ray diffraction.     

Camphor-derived amber/woody odorants: 1,7,7-trimethyl-2′-iso-propylspiro[bicyclo[2.2.1]heptane-2,4′-(1,3-dioxanes)]

Six stereoisomers of a new camphor-derived 1,7,7-trimethyl-2′-iso-propylspiro[bicyclo[2.2.1]heptane-2,4′-(1,3-dioxane)] odorant were prepared. Their design with the help of an amber olfactophore model and structure–odour relationship are reported. The (1R,2S,4R,2′S) isomer has by far the strongest and the most characteristic amber-like odour.     

Synthesis of 4′H-spiro[adamantane-2,3′-isoquinoline] derivatives

Russian Journal of Organic Chemistry -     

The luminescence of the rare earth cryptates [Tb ⊂ 2.2.1]3+ and [Sm ⊂ 2.2.1]3+

The spectroscopic and photophysical properties of [Tb ⊂ 2.2.1]³⁺ and [Sm ⊂ 2.2.1]³⁺ in aqueous solution and the solid state are reported. The role played by multiphonon emission and non-radiative deactivatfon via the excited configuration state in determining the observed luminescence properties is examined.     

Synthesis and Transformation of 5- and 2-Methyl- bicyclo[2.2.1]hept-2-enes and 2-Methylenebicyclo[2.2.1]heptane with Retrospective δ-Migration of Hydrogen over Oxide Catalyst

5-, 2-Methylbicyclo[2.2.1]hept-2-enes, 2-methylenebicyclo[2.2.1]heptane were synthesizedby a new procedure, and their transformations in a flow system over stationary layer of aluminosilicatecatalyst were studied at various temperatures. At 150-400°C these compounds undergo isomerization which is accompanied by -migration of hydrogen. The isomerization mechanism is discussed in terms of formation of classical carbocations, not invoking nonclassical carbenium ion.     

Synthesis of 4′-alkyl-8-azaspiro[bicyclo[3.2.1]octane-3,2′-morpholin]-5′-ones

N-Boc-protected 8-azaspiro[bicyclo[3.2.1]octane-3,2′-oxirane] reacted with primary aliphatic amines through opening of the epoxide ring with formation of the corresponding amino alcohols which were converted into N-chloroacetyl derivatives. The latter underwent cyclization to N-Boc-protected 4′-alkyl-8-azaspiro[bicyclo[3.2.1]octane-3,2′-morpholin]-5′-ones by the action of sodium hydride in DMF, and subsequent treatment with hydrogen chloride in ethyl acetate afforded 8-azaspiro[bicyclo[3.2.1]octane-3,2′-morpholin]-5′-one hydrochlorides.     

Synthesis of 1′-substituted 4′,4′-dimethyl-6′-methoxy-4′H-spiro[cyclohexane-1,3′-isoquinolines]

The reaction of 1-(4-methoxyphenyl)-1-(1-methylcyclohexyl)ethanol with nitriles in concentrated sulfuric acid afforded 1′-substituted 6′-methoxy-4′,4′-dimethyl-4′H-spiro[cyclohexane-1,3′-isoquinolines] as a result of consecutive Wagner-Meerwein rearrangement and Ritter reaction.     

Electrocatalytic multicomponent one-pot approach to tetrahydro-2′H,4H-spiro[benzofuran-2,5′-pyrimidine] scaffold

The new electrocatalytic multicomponent transformation has been found: the electrolysis of arylaldehydes, N,N′-dimethylbarbiturate, and cycloxehane-1,3-diones in alcohols in the presence of sodium bromide as a mediator in an undivided cell results in the formation of substituted unsymmetric spirobarbituric dihydrofurans in 62%–76% yields. The optimized reaction conditions and a mechanistic rationale for this electrocatalytic multicomponent transformation are presented. This new electrocatalytic process is a facile and efficient way to produce substituted unsymmetric spirobarbituric dihydrofurans containing both barbituric and 3,5,6,7-tetrahydro-1-benzofuran-4(2H)-one fragments, which are promising compounds for different biomedical applications, among them are anticonvulsants, anti-AIDS agents, and antiinflammatory remedies. The scaffold approach was employed to find a protein, which may be influenced by the synthesized compounds—human aldose reductase was proposed. It was shown by molecular docking studies that such a scaffold search is beneficial and tetrahydro-2′H,4H-spiro[benzofuran-2,5′-pyrimidines] used in this approach are promising for the development of novel aldose reductase inhibitors.     

Synthesis,Structure and Antimicrobial Activity of 2-Phenyl-4H-spiro[benzo[e][1,4,2]oxaza- phosphinine-3,3′-indolin]-2′-one 2-oxide

A novel spiro-compound(C20 H15 N2 O3 P) has been synthesized and characterized by means of IR and 1H NMR. Its crystal structure was determined by X-ray diffractometry. The crystal belongs to the monoclinic system, space group P21 /c with a = 9.1628(7), b = 12.9490(7), c = 15.7898(11), β = 103.952(8)o, Mr = 36.08, V = 1818.2(2)3, Z = 4, Dc = 1.382 g/cm3, F(000) = 788, μ = 0.179 mm-1, R = 0.0701 and wR = 0.1513. The preliminary biological test showed that the title compound has activities against Escherichia coli, S.albus, Bacillus subtilis, Staphylocc- ocusaureus and Micrococcus tetragenus with MIC to be 0.038, 0.038, 0.075, 2.48, and 0.15 mg/mL, respectively.     

Synthesis and Crystal Structure of 3′-Ethyl 5′-Methyl 1-Benzyl-4′-methyl-2-oxo-3′,4′-dihydrospiro-[indoline-3,2′-pyrrole]-3′,5′-dicarboxylate

The crystal structure of the title compound(C24H24N2O5, Mr = 420.45) has been determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P1 with a = 8.991(1), b = 11.166(1), c = 11.169(1) , α = 91.413(2), β = 105.887(2), γ = 90.992(2)°, V = 1077.8(2) 3, Z = 2, Dc = 1.296 g/cm3, F(000) = 444, μ(MoKα) = 0.091 mm-1, the final R = 0.0466 and wR = 0.1507 for 4185 observed reflections(I 2σ(I)). The single-crystal X-ray diffraction data indicated intermolecular C(17)–H(17)O(4), C(5)–H(5)… O(4) hydrogen bonds and C–H…π interaction in the structure.     

α-Fluorination of 6-phenylsulfinyl-2-azabicyclo[2.2.1]heptan-3-one and synthesis of 2′-fluoro substituted carbovir

Fluorination of phenylsulfinyl bicycloamide using molecular fluorine proceeded preferentially with inversion of the carbon atom having the sulfinyl group to afford α-fluorinated sulfonyl bicycloamide in fair yield. The fluorinated sulfonyl bicycloamide was converted to 2′-fluoro substituted carbovir via reductive desulfonylchlorination.     

Chiral Brønsted acid-catalyzed enantioselective ionic [2+4] cycloadditions

The first asymmetric chiral N-triflylphosphoramide-catalyzed ionic [2+4] cycloaddition reaction of unsaturated acetals is described. This reaction proceeds through the intermediacy of a vinyl oxocarbenium/chiral anion pair, and the chiral N-triflylphosphoramide anion controls the stereoselectivity of the cycloaddition step. Moderate enantioselectivities (up to 80:20 e.r.) have been obtained when α,β-unsaturated dioxolanes were employed as the dienophiles. These reactions demonstrate strong dependence on the counterion coordinating properties and solvent polarity, a behavior characteristic of oxocarbenium ions.     

The application of copolymer-coated graphene oxide-Fe3O4 in the highly efficient synthesis of 2′-aminospiro[indeno[1,2-b]quinoxaline-11,4′-[4'H] pyran]-3′-carbonitrile and 2′-aminospiro[indeno-2,4′-[4'H]pyran]-3′-carbonitrile

A magnetic nanocomposite based on graphene oxide was prepared. Fe₃O₄ nanoparticles were loaded on graphene oxide sheets and GO-Fe₃O₄ was covered by aniline-pyrrole copolymer to afford poly(Py-co-Ani)@GO-Fe₃O₄. This nanocomposite was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy techniques, and its catalytic activity was evaluated in the multicomponent synthesis of 2′-aminospiro[indeno[1,2-b]quinoxaline-11,4′-[4'H]pyran]-3′-carbonitrile and 2′-aminospiro[indeno-2,4′-[4'H]pyran]-3′-carbonitrile derivatives. This magnetically separable catalyst is heterogeneous noncorrosive, highly efficient, and reusable.     

Synthesis of novel 2H-spiro[1-benzofuran-3,4′-piperidin]ol scaffolds

With the aim to enrich our ‘privileged structure’-based library, novel 2H-spiro[1-benzofuran-3,4′-piperidin]ol scaffolds were prepared. The method involved a key intramolecular Heck cyclization which was successfully applied for three series of compounds. The desired scaffolds were obtained in overall yields of 42–53%.     

Structure and Properties of 1,3,3-Trimethyl-6′-chlorospiro[indoline-2,2′-2H-chromene]

Russian Journal of General Chemistry - Indoline spiropyran containing an σ-acceptor chlorine atom in 6′ position of the 2H-chromene part of the molecule was synthesized and studied. The...     

Access to 2′,3′-dihydro-1′H-spiro[indoline-3,4′-pyridin]-2-ones via amino acid derived phosphine-catalyzed asymmetric [4+2] annulation with easily available oxindole-derived α,β-unsaturated imines

The phosphine-catalyzed asymmetric [4+2] annulation of vinyl ketones with more easily available oxindole-derived α,β-unsaturated imines has been further developed in the presence of an easily available multifunctional thiourea-phosphine catalyst derived from natural amino acid, providing the enantioselective synthesis of 2′,3′-dihydro-1′H-spiro[indoline-3,4′-pyridin]-2-ones in good yields and moderate de values with higher enantioselectivities under mild conditions.     

Synthesis of β- and γ-carbolines via ruthenium and rhodium catalysed [2+2+2] cycloadditions of yne-ynamides with methylcyanoformate

A flexible approach towards substituted β- and γ-carbolines based on transition metal catalysed [2+2+2] cycloaddition reactions between functionalised yne-ynamides and methylcyanoformate is described. The versatility of this new reaction sequence is demonstrated by its application in the total synthesis of the marine natural product eudistomin U.     

Synthesis and Crystal Structure of Spiro[1-bromo-4-methoxy-5-oxa-6-oxo-bicyclo[3.1.0]hexane-2,2′-（3′- cyclohexanoxy-4′-methoxybutyrolactone]

1INTRODUCTIONThecyclopropane-containingnaturalproductshavereceivedconsiderableattentionassynthetictar-getsastheincorporationofrigidifiedcyclopropylmotifintobioactiveanaloguescanleadtoconfor-mablyconstrainedmolecules[1,.Suchmodifica-2]tionsareexpectedtohavesignificanteffectsonbio-activitieswithconcomitantmedicalimplications.Des-pitethegreatadvancesinthisfield,theefficientsyn-thesisofspiro-cyclopropanecompoundsstillremainsaconsiderablechallenge.Particularnoticeisthede-ficiencyinthepreviousm…