Regiochemically controlled syntheses of 3-hydroxynaphtho [b] cyclobutene by vicinal diester dianion condensation.

Utilization of the dianion derived from dimethyl $\text{trans}$-1,2-cyclobutane dicarboxylate allows for the rapid construction of an unsymmetric naphtho [b] cyclobutene by two different routes.     

3-methylthio-1,2-dithiolylium salts : Reaction with 4-hydroxy-6-methyl-2H-pyran-2-one and 4-hydroxycoumarin

The reaction of 4- and 5-aryl-3-methylthio-1,2-dithiolylium iodides with 4-hydroxy-6-methyl-2$\text{H}$-pyran-2-one and 4-hydroxycoumarin has been studied. 4-Substituted salts yielded 3-aryl-7-methyl-2-thioxo-2$\text{H}$,5$\text{H}$-pyrano [3,2-c]pyran-5-ones and 3-aryl-2-thioxo-2H,5H-pyrano[3,2-c]benzo[e]pyran-5-ones, respectively, whereas 5-substituted salts gave rise to 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-6-methyl-2$\text{H}$-pyran-2,4-diones and 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-2$\text{H}$-benzo [b]-pyran-2,4-diones.     

Photochemical studies. Irradiation induced transformations of 1,2-dihydrophthalides

The photochemical behavior of $\text{cis}$-1,2-dihydrophthalide ($\text{1}$) and its 1,2-trimethylene derivative ($\text{4}$) was studied. Besides bicyclo[2.2.0]hexene formation in both cases, ($\text{1}$) transforms into its $\text{trans}$ isomer ($\text{3}$) whereas ($\text{4}$) undergoes a 1,2-shift to ($\text{7}$).     

Studies in azide chemistry. Part 12. One-pot conversion of 4-azidotetrafluoropyridine to 1,3,4-trifluoro-7,9-dimethyl-11H-pyrido[4,3-c]benzo[1,2]diazepine

Thermolysis of 4-azidotetrafluoropyridine in the presence of an excess of mesidine at 170 °C yields tetrafluoro-4-(2,4,6-trimethylphenylazo)- pyridine, which undergoes intramolecular dehydrofluorination $\text{in situ}$ to provide 1,3,4-trifluoro-7,9-dimethyl-11$\text{H}$-pyrido[4,3-$\text{c}$]benzo[1,2]diazepine.     

Chemistry of benzo[6-b]selenophene III. Selenoindoxyl derivatives

3-Acetoxybenzo[b]selenophene and its 2-methyl derivative, respectively, were synthesized by the cyclization of o-carboxyphenylselenoacetic and-(o-carboxyphenyl)selenopropionic acids. 3-Hydroxy-2,3-dihydrobenzo[b]selenophene and its 2-methyl derivatives were obtained by the reduction of selenoindoxyl and 2-methylselenoindoxyl with sodium borohydride. 3-Methyl-3-hydroxy-2,3-dihydrobenzo[b]selenophene was synthesized by the reaction of selenoindoxyl with methylmagnesium iodide.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1640–1644, December, 1971.     

Chemistry of benzo[b]selenophene

The bromination of benzo[b]selenophene with an equimolecular amount of bromine and its acetylation with acetic anhydride in the presence of boron trichloride etherate proceed to form a mixture of isomeric 2- and 3-substituted derivatives; 2,3-dibromobenzo[b]selenophene is formed on bromination with two equivalents of bromine. Benzo[b]selenophene-2-carboxylic acid, its acid chloride and methyl ester, as well as 2-acetylbenzo[b]selenophene, were synthesized from the lithium derivative of benzo[b]selenophene.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 15–19, January, 1972.     

Reaction of dicarbonyl compounds with dimethyl 3-ketoglutarate. Influence of steric effects on success of the condensation

The influence of steric factors on the synthesis of substituted bicyclo[3.3.0]octane-3,7 diones $\text{via}$ the condensation of 1,2-dicarbonyl compounds with dimethyl 3-ketoglutarate $\text{2}$ is described.     

Synthesis applications of aza-cope rearrangements.: Stereocontrolled synthesis of cyclohepta [b]pyroolidines1

Both $\text{cis}$- and $\text{trans}$-3a-aryl-4-oxo-decahydrocyclohepta[b]pyrroles can be prepared in stereocontrolled fashions by the reaction of 2-amino-1-(1-phenyl- vinyl)cyclohexanols with formaldehyde and acid.     

Reactions stereoselectives des alkylmagnesiens secondaires avec les anhydrides et lactones rigides

High stereoselectivity was observed in the reactions of secondary alkylmagnesium compounds with bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride $\text{1}$ and lactone 2 leading respectively to the formation of $\text{trans}$ diastereomeric lactones and $\text{erythro}$ primary-secondary diols.     

Electronic control of stereoselectivity-21 : Stereochemical parallelism between dienophilic capture and singlet oxygenation of isodicyclopentadiene derivatives

The stereochemistry and product distribution resulting from reaction of 4',5',6',7'- tetrahydrospirol[cyclopropane-1,2']-[4,7]methano[2$\text{H}$]indene(5), endo-2-methyl(6a) and 2,2-dunethyl-4,7-dihydro-4,7-methano-2$\text{H}$-indene (6b), as well as 4',5',6',7'-tetrahydrospiro[cyclopentane-1,2']-[4,7]methano-[2$\text{H}$]indene (7) with singlet oxygen have been determined. Stereochemical assignments to the diepoxide products were readily deduced by ¹³C-NMR comparison with the spectra of the parent isomcrs of established structure (X-ray). To unravel the stereochemistry of the epoxy aldehydes, recourse was made to 2D NOE experiments The observed stereosclectivity and reaction profile of each substrate are analyzed and placed in proper mechanistic and energetic perspective.     

1,5-Bis(trimethylsiloxy)-1,5-dimethoxy-1,4-pentadienes. cyclopropane synthesis via intramolecular coupling.

The title compounds ($\text{1}$a–e) can be prepared in good yield by silylation of the dianions of dimethyl glutarates ($\text{2}$a–e). On treatment with titanium tetrachloride, they cyclise stereoselectively to dimethyl $\text{trans}$-cyclopropane-1,2-dicarboxylates.     

Synthesis of benzo[b]selenophene and its methyl homologs

A method for the synthesis of benzo[b]selenophenes was perfected. 3-Oxo-2,3-dihydrobenzo[b]selenophene and 2-methyl-3-oxo-2,3-dihydrobenzo[b]selenophene exist only in the keto form. 3-Methylbenzo[b]selenophene was obtained by the reaction of 3-oxo-2,3-dihydrobenzo[b]selenophene with methylmagnesium iodide. Metallation of benzo[b]selenophene with butyllithium proceeds at the 2 position of the selenophene ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1475–1480, November, 1970.     

Cross-conjugated biradicals: Kinetics and kinetic isotope effects in the thermal isomerizations of cis- and trans-2,3-dimethylemethylnecyclopropane,cis- and trans-3,4-dimethyl-1,2-dimethylenecyclobutane,and of 1,2,8,9-decatetraene

cis- and trans - 2,3 - Dimethylenemethylenecyclopropane ($\text{C}$ and $\text{T}$) interconvert at 160.0° with a small normal kinetic isotope effect (KIE) when the exo-methylene is deuterated, but the 1,3-shift products, 2-methylethylidenecyclopropane, show a large normal KIE, 1.35 and 1.31, when formed from $\text{C}$ and $\text{T}$, respectively. This data can be interpreted in terms of either parallel reactions or a common trimethylenemethane diradical intermediate formed with a normal KIE of 1.11 and closing to 1,3-shift product with a normal KIE of 1.29 due to the effect of deuterium in the required 90° rotation of the exo-methylene carbon.The kinetics of the thermal 1,3- and 3,3-shifts of cis- and rans-3,4-dimethyl-1,2-dimethylenecyclobutane ($\text{CB}$ and $\text{TB}$) were determined in a flow reactor. The first order rate constants are log k_CB (sec^?1) = 13.7 ? 42,200/2.3 RT and log k_TB (sec^?1) = 13.6 ? 41,900/2.3 RT (E_a in kcal/m) which compare favorably to that from the parent hydrocarbon. 1,2-dimethylenecyclobutane, after reasonable correction for dimethyl substitution.Rearrangement of $\text{TB}$ and its bis(dideuteriomethylene) derivative at 230.0° revealed a normal KIE of 1.08. This KIE could be interpreted in terms of either a methylene rotational isotope effect in a concerted reaction or formation of a bisallyl diradical with the expected normal rotational IE on closure to the 1,3-shift product of 1.12 with no IE in the ring opening when the result is corrected for return of the biradical to starting material.The kinetics of intramolecular 2 + 2 cycloaddition of 1,2,8,9-decatetraene were determined in a flow reactor. The first order rate constant is log k(sec^?1) = 9.4 ? 30,800/2.3 RT (E_a in kcal/m). These energetics are compared with those of other 2 + 2 cycloadditions. The major product is 3,4-dimethylenecyclooctene ($\text{DC}$) which is also found from the minor product, cis-7,8-dimethylenebicvyclo[4.2.0]octane ($\text{CO}$), at higher temperatures. The trans isomer, $\text{TO}$, also gives $\text{DC}$ at about the same rate as $\text{CO}$.     

Photoaddition reactions of trans dichloroethylene with benzenoid compounds: facile formation of tetracyclo[3.3.0.02,804,6]octanes and semibullvalenes

$\text{trans}$ 1,2-Dichloroethylene undergoes a stereospecific photoreaction with benzonitrile, the three tolunitriles, α,α,α-trifluorotoluene, fluorobenzene, and chlorobenzene to give substituted 6-$\text{exo}$ 7-$\text{endo}$ dichlorotricyclo[3,3,0,0_2,8]oct-3-enes which on treatment with base yield cyclised products or semibullvalenes: phenol yields dichlorobicyclo[3.2.1]oct-2-en-8-one with this ethylene photochemically.     

Spectres photoélectroniques He(I) et He(II) du benzo[b]sélénophène et du benzo[b]tellurophène

He(I) and He(II) photoelectron spectra of benzo[b]selenophene and benzo[b]tellurophene The photoelectron spectra of benzo[b]selenophene ( 2 ) and benzo[b]tellurophene ( 1 ) have been recorded with He(I) and He(II) radiation and been compared to those of benzo[b]thiophene ( 3 ), benzo[b]furan ( 4 ), indole ( 5 ) and indene ( 6 ). The first four bands are correlated with π-orbitals, of which the highest occupied one is strongly localized on the heteroatom in the case of 1 . The results are in agreement with semi-empirical PPP-calculations.     

Potential metabolites of carcinogenic aza aromatic hydrocarbons synthesis of K-region oxide,phenol and dihydrodiols of 7-methylbenz[c]acridine

The potential K-region metabolites, $\text{trans}$- and $\text{cis}$-5,6-dihydroxy-7-methyl-5,6-dihydrobenz[c]acridine, 5,6-epoxy-7-methyl-5,6-dihydrobenz[c]acridine and 5-hydroxy-7-methylbenz[c]acridine, of 7-methylbenz[c]acridine have been synthesised.     

Alicyclische verbindungen-v. darstellung diverser 1,3-butadienylcyclobutane

$\text{cis}$-($\text{3}$) and $\text{trans}$-1,3-Butadienylcyclobutane ($\text{4}$), all-$\text{trans}$-1-(1 ,3-butadieny1 )-2- vinylcyclobutane ($\text{10}$), and all-$\text{trans}$-1,2-bis(1,3-butadienyl)cyclobutane ($\text{15}$) have been prepared from readily available starting materials, and pyrolyzed to various cyclohexenes.     

Fluorocarbon derivatives of nitrogen. Part 11. Synthesis of some 2-(trifluoromethyl)imidazo[1,2-a]pyridines from trifluoroacetonitrile

3-(t-Butoxycarbonyl)-2-(trifluoromethyl)imidazo[1,2-$\text{a}$]-pyridine, prepared from trifluoroacetonitrile and pyridinium t-butoxycarbonylmethylide, reacts smoothly with trifluoroacetic acid to provide 2-(trifluoromethyl)imidazo[1,2-$\text{a}$]pyridine-3-carboxylic acid, which gives 2-(trifluoromethyl)imidazo[1,2-$\text{a}$]-pyridine when heated. 3-Cyano-2-(trifluoromethyl)imidazo[1,2-$\text{a}$]pyridine can be obtained $\text{via}$ treatment of trifluoroacetonitrile with pyridinium cyanomethylide, which is sufficiently reactive to effect nucleophilic displacement of fluorine from pentafluoropyridine under mild conditions [→pyridinium cyano(tetrafluoro-4-pyridyl)methylide].     

Photo-Induced diels-alder reaction. A novel route to trans fused benzobicyclo-[5.3.O]decanes and [5.4.O]undecanes

Photoisomerization of $\text{cis}$-benzocycloheptenone to $\text{trans}$ benzocycloheptenone and its [4 + 2] cycloaddition with selected dienes is reported for the synthesis of $\text{trans}$ fused benzobicyclo[5.3.0]decanes 10, 12 and benzobicyclo [5.4.0]undecanes 13, 15.     

The octant rule. XVI1. COnformation and circular dichroism of syn and anti 2-methylbicyclo[3.1.0]hexan-3-ones,thujone and isothujone

(lS,5S)-exo-2(R)-Methylbicyclo[3.1.0]hexan-3-one ($\text{1}$) and (lS,5S)-endo-2(S)-methylbicyclo[3.1.0]hexan-3-one (2) were synthesized and their circular dichroism (CD) spectra run. Conformational analysis based on molecular mechanics calculations and Karplus equation analyses of vicinal H¦H NMR coupling constants indicate boat-like sofa conformations for both $\text{1}$ and $\text{2}$, with very little ring distortion from the symmetry of the parent bicyclo[3.1.0]hexan-3-one. The lone dissymmetric ψ-axial and ψ-equatorial methyl groups of $\text{1}$ and $\text{2}$, respectively, are both octant consignate. The natural product analogs of $\text{1}$ and $\text{2}$, (?)-3-isothujone ($\text{3}$) and (+)-3-thujone ($\text{4}$) were prepared and examined similarly. Their α-methyl perturbers dominate the CD n-π^★ Cotton effects.