13C-NMR-spektren von spiro[2.4]hepta-(1,4,6)-trienen und -(4.6)-dienen

The ¹³C NMR spectra of [1.2]-spirenes 2 and spiro[2.4]hepta-(4.6)-dienes 5 are described and the effects of substituents are discussed. A bonding model of the [1.2]-spirenes 2 is derived on the basis of C-H coupling constants and calculated charge densities. The ¹³C NMR shifts of 1-aryl-spiro[2.4]hepta-(4.6)-dienes 6 show a good correlation with the Hammett σp constants of the substituents in p-position of the phenyl ring. Conclusions on spiroconjugation in [1.2]-spirenes 2 are drawn from comparing the ¹³C shifts of similar substituted [1.2]-spirenes and spiro[2.4]hepta-(4.6)-dienes. The spiroconjugation in [1.2]-, [2.2]- and [2.3]-spirenes 2, 3 and 4 is discussed comparing the calculated charge densities with the δ (¹³C) values, as well as the UV and p.e. spectra.     

The formation of tetracyclo[7.2.1.02,5.02,8]dodeca-6,10-dienes under conditions of thermal isomerization of spiro[2.4]hepta-4,6-diene into bicyclo[3.2.0]hepta-1,3-diene

The formation of the novel hydrocarbons, tetracyclo[7.2.1.0^2,5.0^2,8]dodecadienes, as a result of thermal isomerization of spiro[2.4]hepta-4,6-diene into bicyclo[3.2.0]hepta-1,3-diene and its capture by 1,3-dienes is demonstrated. The conditions of thermal isomerization and dimerization of the spiroheptadiene are studied. Cyclopropanation of the polycyclic dienes formed by diazomethane in the presence of Pd-catalysts was accomplished, and occured solely through the norbornene double bond.For preliminary communication see ref.¹ Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 132–137, January, 1993.     

A novel bornane synthesis by an old idea

Aiming at a synthesis of spiro[2.4]hepta-4,6-dienes with a carbon substituent at C-4, we investigated solvolysis reactions of the thiatricycle 2, obtained from spiro[2.4]hepta-4,6-diene (1) and thiophosgene by [4 + 2] cycloaddition. With methanol or ethanol a mixture of the esters 7 and 8 was formed. Desulfurization of the thionoesters 8 gave methyl and ethyl spiro[2.4]hepta-4,6-diene-4-carboxylate (10a,b). The corresponding alcohol (11) was prepared from 10b by LiAlH(4) reduction. Ethenetetracarbonitrile combined with the 4-substituted spiro[2.4]hepta-4,6-dienes to give the [4 + 2] cycloadducts 12a-c. Diels-Alder reaction between 11 and 2-chloroacrylonitrile afforded the spiro(bicyclo[2.2.1]hept-5-ene-7,1'-cyclopropane) derivative 14a that was transformed in three steps to rac-10-hydroxycamphor (17). This synthesis of a bornane derivative opens opportunity for variations and thus may find further applications.     

Desymmetrization of meso 7-aza-2,3-bis(phenylsulfonyl) bicyclo[2.2.1]hept-2-ene: a re-examination. Kinetic resolution of racemic 3-arylsulfonyl-7-aza-2-bromobicyclo[2.2.1]hepta-2,5-dienes

The inexpensive large scale preparation of N-methoxycarbonyl-7-aza-2,3-bis(phenylsulfonyl)bicyclo[2.2.1]hept-2-ene and the re-examination of its stereoselective desymmetrization are reported. Moreover, the kinetic resolution of N-protected 3-arylsulfonyl-7-aza-2-bromobicyclo[2.2.1]hepta-2,5-dienes promoted by (R,R)-hydrobenzoin is described, representing a new tool to fix the absolute stereochemistry of the 7-azabicyclo[2.2.1] skeleton.     

Synthesis and Photoinitiated Isomerizations of 3-(4-Nitrophenyl)-and 3-(4-Aminophenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbaldehyde and -2-carboxylic acid Derivatives

3-(4-Nitrophenyl)bicyclo[2.2.1]hepta-2,5-diene-2-carbaldehyde and its derivatives at the formyl group were synthesized. By reduction of the nitro group the corresponding 3-(4-aminophenyl)-substituted compounds were obtained, as well as 4,4'-bis(bicyclo[2.2.1]hepta-2,5-dien-2-yl)azobenzenes. Irradiation of the resulting norbornadiene derivatives in the region of their absorption maxima resulted in valence isomerization with formation of the corresponding quadricyclanes. The reverse transformations are promoted by molybdenum(VI) oxide as heterogeneous catalyst. 4,4'-Bis(bicyclo[2.2.1]hepta-2,5-dien-2-yl)azobenzenes undergo reversible (on heating) photochemical EZ/ isomerization at the NÍN bond.     

Expanding the C2-symmetric bicyclo[2.2.1]hepta-2,5-diene ligand family: concise synthesis and catalytic activity in rhodium-catalyzed asymmetric addition

New C2-symmetric bicyclo[2.2.1]hepta-2,5-dienes bearing methyl and phenyl substituents at the 2 and 5 positions were prepared enantiomerically pure through a two-step sequence starting from the readily available bicyclo[2.2.1]hepta-2,5-dione. Due to the instability or volatility of these dienes, their isolation was achieved through the formation of the corresponding stable [RhCl(diene)]2 complexes. These chiral rhodium complexes displayed high activity and enantioselectivity (up to 99% ee) in the rhodium-catalyzed 1,4-addition and 1,2-addition of phenylboronic acid to cyclic enones and N-sulfonylimines, respectively.     

Thermal [2+2] cycloaddition of allenynes: easy construction of bicyclo[6.2.0]deca-1,8-dienes, bicyclo[5.2.0]nona-1,7-dienes, and bicyclo[4.2.0]octa-1,6-dienes

The simple refluxing of allenynes, having a phenylsulfonyl functionality on the allenyl group, in xylene (or mesitylene) without microwave irradiation resulted in the efficient formation of bicyclo[5.2.0]nona-1,7-dienes and bicyclo[4.2.0]octa-1,6-dienes in high yields. This method was shown to be successfully applicable to the first construction of bicyclo[6.2.0]deca-1,8-dienes. Construction of the corresponding oxa- and azabicyclo[m.2.0] frameworks could also be attained. This thermal ring-closing reaction involves the formal [2+2] cycloaddition in which the distal double bond of an allenyl moiety exclusively served as one of the pi-components regardless of the position of the phenysulfonyl functionality on the allenyl moiety.     

Synthesis of 7‐azabicyclo[2.2.1]heptane derivatives by transformation of tropinone

The bromination (CuBr₂, AcOEt/CHCI₃) plus Favorskii rearrangement (EtONa, EtOH) of N‐carbethoxytropinone ( 4 ), readily available from tropinone ( 3 ), affords mixtures of exo‐ and endo‐isomers of 2,7‐dicarbethoxy‐7‐azabicyclo[2.2.1]heptane ( 1b ) in variable and moderate chemical yield (maximum 37%). The bromination (Br₂, HBr/AcOH) reaction of compound 4 gives ethyl trans‐2,4‐dibromo‐3‐oxo‐8‐azabicyclo[3.2.1]octane‐8‐carboxylate ( 5 ) in 99% yield, a product that on Favorskii rearrangement (EtONa/EtOH) affords ethyl 2,2‐diethoxy‐3‐oxo‐8‐azabicyclo[3.2.1]octane‐8‐carboxylate in moderate yield ( 6 ) (52%).     

Photochemical and thermal transformations of 7-silabicyclo[2.2.1]Heptadiene and 7-silabicyclo[2.2.1]heptene systems

2,3-Dicarbomethoxy-7,7-dimethyl-7-silabicyclo[2.2.1]hepta-2,5-diene (III) on photolysis gave dimethyl tetraphenylphthalate whereas the photolysis of 7,7-dimethyl-7-silabicyclo[2.2.1]hep-5-ene-2,3-dicarboxylic anhydride (XIa) resulted in the formation of 1,1-dimethyl-2,3,4,5-tetraphenyl-1-silacyclopentadiene (XIIIa). The thermolysis of XIa also gave rise to XIIIa. Similarly, the photolysis as well as thermolysis of 1,4,5,6,7,7-hexaphenyl-7-silabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (XIb) led to hexaphenylsilacyclopentadiene (XIIIb). Attempts to detect radical intermediates in these thermal and photochemical transformations by carrying out the reaction in the presence of hydroquinone, hydrazobenzene, 3,6-diphenyl-1,2-dihydro-1,2,4,5-tetrazine, cumene and tolan were unsuccessful. An attempted preparation of 7-silabicyclo[2.2.1]hepta2,5-dienes by the reaction of silacyclopentadienes such as 1-methyl-1-vinyl2,3,4,5-tetraphenyl-1-silacyclopentadiene (XV) and 1-methyl-1,2,3,4,5-pentaphenyl-1-silacyclopentadiene (XVI) with dimethyl acetylenedicarboxylate resulted in the isolation of dimethyl tetraphenylphthalate indicating that the corresponding 7-silabicyclo[2.2.1]hepta-2,5-dienes are thermally unstable.     

Synthesis of <Emphasis Type="Italic">para</Emphasis>-substituted 1,4,5,6,7,7-hexachlorobicyclo-[2.2.1]hepta-2,5-dien-2-ylmethyl benzoates

[4 + 2]-Cycloaddition of hexachlorocyclopentadiene to para-substituted prop-2-yn-1-yl benzoates gave the corresponding 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hepta-2,5-dien-2-ylmethyl benzoates. The structure of the adducts was confirmed by independent synthesis, esterification of para-substituted benzoic acids with 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hepta-2,5-dien-2-ylmethanol.     

Synthesis of 1‐azabicyclic systems by double cyclization

5‐Cyano‐1‐azabicyclo[3.3.0]octane ( 1 ) was prepared in one step from 1,7‐dichloro‐4‐heptanone ( 4 ) under mild conditions. The application of this method for the preparation of 5‐cyano‐4,6‐dimethyl‐1‐azabicy‐clo[3.3.0]octane ( 11 ) gave two diastereomers in equilibrium. The NMR measurements of 11 and its reduced compound 15 showed that the major isomer is the cis‐exo form, and the minor isomer is the trans form. Molecular orbital calculations indicated that the cis‐exo form is more stable than the trans form, in agreement with the experimental results. Furthermore, 6‐cyano‐1‐azabicyclo[4.3.0]nonane ( 17 ) and 1‐azabicy‐clo[4.4.0]decane ( 19 ), both including a six‐membered ring, were prepared from appropriate haloketones by using this double cyclization method.     

Aza-di-π methan-umlagerungen ?

2,6-Diazabicyclo[3.2.o]hepta-2,6-dienes 3 are isolated as intermediates in the phototransformation of 4H-1,2-diazepines 1 to 6H-1,4-diazepines 4/5.★★)     

Kinetic characterization of a transient reaction by degeneration of the precursor mechanism: Application to the synthesis of 3,4‐diazabicyclo[4.3.0]‐ non‐2‐ene

The rate of the oxidation of N‐amino‐3‐azabicyclo[3.3.0]octane by chloramine has been studied by GC and HPLC between pH 10.5 and 13.5. The second‐order reaction exhibits specific acid catalysis. The formation of N,N′‐azo‐3‐azabicyclo[3.3.0]octane or 3,4‐diazabicyclo[4.3.0]non‐2‐ene is pH, concentration, and temperature dependent. In alkaline media, the exclusive formation of 3,4‐diazabicyclo[4.3.0]non‐2‐ene is observed. Kinetic studies show that the oxidation of N‐amino‐3‐azabicyclo[3.3.0]octane by chloramine is a multistep process with the initial formation of a diazene‐type intermediate, which is converted by hydroxide ions into 3,4‐diazabicyclo[4.3.0]non‐2‐ene. Because it was not possible to follow the rate of change of the intermediate concentration, to determine the kinetics of 3,4‐diazabicyclo[4.3.0]non‐2‐ene formation, a procedure based on the degeneration of the precursor process was adopted. An appropriate mathematical treatment allowed a quantitative interpretation of all the phenomena observed over the given pH interval. The activation parameters were determined. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 327–338, 2006     

Herrmann-Beller phosphapalladacycle-catalyzed addition of alkynes to norbornadienes

Herrmann-Beller (H-B) phosphapalladacycle selectively catalyzed the addition of terminal alkynes across one double bond of norbornadiene to afford exo-5-alkynyl-bicyclo[2.2.1]hept-2-enes. The reaction shows general applicability to various functionalized alkynes and bicyclo[2.2.1]hepta-2,5-dienes. Insights into the mechanism of this reaction are discussed.     

Product structure in the reaction of dimethyl acetylenedicarboxylate with 2-furyl-1,2,3,4-tetrahydroquinolines

Dimethyl acetylenedicarboxylate reacts with 4-substituted and 3,4-fused 2-furyl-1,2,3,4-tetrahydroquinoline derivatives at the furan fragment according to the [4 + 2]-cycloaddition pattern. The reaction is not stereoselective, and it yields two diastereoisomeric 7-oxabicyclo[2.2.1]hepta-2,5-dienes whose structure was determined by X-ray analysis and NMR spectroscopy.     

Synthesis of novel azabicyclo derivatives containing a thiazole moiety and their biological activity against pine-wood nematodes

Abstract

To explore a new skeleton with nematicidal activity, a series of novel azabicyclo derivatives containing a thiazole moiety were designed, synthesized and evaluated for their nematicidal activities. The bioassay results against pine-wood nematodes (Bursaphelenchus xylophilus) showed that most of the title compounds displayed nematicidal activity at a concentration of 40?mg/L. Especially, the title compounds2-((8-methyl-8-azabicyclo[3.2.1]octan-3-yl)oxy)-4-(4-chlorophenyl)thiazole (7e), 2-((8-methyl-8-azabicyclo[3.2.1]octan-3-yl)thio)-4-phenylthiazole (10a) and 2-((8-methyl-8-azabicyclo [3.2.1]octan-3-yl)thio)-4-(4-chlorophenyl)thiazole (10e) exhibited more than 90% mortality against Bursaphelenchus xylophilus.     

Preparation of novel azabicyclic amines and α7 nicotinic acetylcholine receptor activity of derived aryl amides

Three new azabicyclic amines, namely exo‐3‐amino‐1‐azabicyclo[3.2.1]octane, 3‐amino‐1‐azabicyclo‐[3.2.2]nonane and exo‐6‐amino‐8‐azabicyclo[3.2.1]octane, have been designed and prepared as isosteres of 3‐aminoquinuclidine. Aryl amides derived from each series were prepared and tested in an α7 nicotinic acetylcholine receptor assay as part of a drug discovery program to treat the cognitive deficits in schizophrenia. All new amides showed significant α7 nAChR activity and one series displayed potent α7 activity equal to the quinuclidine series.     

The First Ring‐Enlargement of a 1‐Azabicyclo[1.1.0]butane to a 1‐Azabicyclo[2.1.1]hexane

The reactions of 3‐phenyl‐1‐azabicyclo[1.1.0]butane ( 4 ) with dimethyl dicyanofumarate ((E)‐ 8 ) and dimethyl dicyanomaleate ((Z)‐ 8 ) lead to the same mixture of cis‐ and trans‐4‐phenyl‐1‐azabicyclo[2.1.1]hexane 2,3‐dicarboxylates (cis‐ 11 and trans‐ 11 , resp.; Scheme 3). This result of a formal cycloaddition to the central C? N bond of 4 is interpreted by a stepwise reaction mechanism via a relatively stable zwitterionic intermediate 10 , which could be intercepted by morpholine to give a 1 : 1 : 1 adduct 12 , which undergoes a spontaneous elimination of HCN to yield the fumarate 13 (Scheme 4).     

Hexafluorothioacetone based synthesis of fluorinated heterocycles

Cycloadducts of hexafluorothioacetone (HFTA) were prepared in high yield by a CsF catalyzed reaction between readily available 2,2,4,4-tetrakis-(trifluoromethyl)-1,3-dithietane (as a source of HFTA) with conjugated electron-rich hydrocarbon dienes, such as cyclopentadiene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene or (1Z,3Z)-cyclohepta-1,3-diene. Cyclohexa-1,4- and (1Z,5Z)-cycloocta-1,5-dienes, also undergo the reaction with in situ generated HFTA, but form the products of insertion of HFTA into the C-H bond of the diene as a result of ene-reaction. The highly selective reaction of HFTA with (1Z,3Z,5Z)-cyclohepta-1,3,5-triene and (1Z,3Z,5Z,7Z)-cycloocta-1,3,5,7-tetraene leads to the formation of cycloadducts derived from exclusive addition of thioacetone to the corresponding bicyclic isomers—bicyclo[4.1.0]hepta-2,4-diene or bicyclo[4.2.0]octa-2,4,7-triene, respectively. The corresponding cycloadducts of HFTA with 2,3-dimethylbutadiene-1,3-cyclohexa-1,3-cyclohexa-1,4-dienes and (1Z,3Z,5Z)-cyclohepta-1,3,5-triene were also prepared by direct reaction of sulfur/hexafluoropropene/KF and the corresponding hydrocarbon substrate at 35-45 °C in DMF.     

Preparation of 1-vinyl-substituted spiro[2.4]hepta-4,6-dienes by the cycloalkylation of cyclopentadiene using 1,4-dihalo-2-alkenes under phase-transfer catalysis conditions

Conclusions The cycloalkylation of cyclopentadiene by 1,4-dihalo-2-alkenes under phase-transfer catalysis conditions gives 1-vinyl- and 1-(1-propenyl)spiro[2.4]hepta-4,6-dienes in 55–60% yield.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 949–950, April, 1985.