Diels-alder reactions of methyl- and π-acceptor-substituted 2-vinylindoles with dimethyl acetylenedicarboxylate and tetracyanoethylene: Novel functionalized carbazoles

The Diels-Alder reactions of the 2-vinylindoles 1a-1d , which are now readily accessible, with dimethyl acetylenedicarboxylate and tetracyanoethylene give rise to the novel 1,2-dihydro- and 1,2,3,4-tetrahydrocarbazoles 2, 4 , and 5 as well as the fully aromatized carbazoles 3 . With regard to the product spectrum, the mechanistic rationale comprises a Diels-Alder step, formal 1,3-hydrogen shift, ene reaction, and dehydrogenation. Conformational aspects of the 1,2-dihydrocarbazoles 2b and 2c are also discussed.     

[4+2]Cycloadditions of organometallic-substituted siloles with dimethyl acetylenedicarboxylate and tetracyanoethylene

1-Sila-2,4-cyclopentadienes (siloles) bearing five organyl groups and a diethylboryl group in 3-position (3), four organyl groups, a trimethylstannyl and a diethylboryl group in 2,4-positions (4), four organyl groups, a diethylboryl group in 3-position and a hydrido function at the silicon atom (5) react by [4+2]cycloaddition with dimethyl acetylenedicarboxylate, MeOC(O)CCC(O)OMe (1), and tetracycanoethylene, (NC)₂CC(CN)₂ (2), to give 7-silanorbornadienes (6–8) and 7-silanorbornenes (10–12), respectively. The silole 5 is converted into isomers 8 and 8′, and 12 and 12′, in which the SiMe group in each major isomer (8 and 12) occupies the syn-position with respect to the C(2)C(3) bond. The molecular structure of 10a was determined by X-ray analysis. The 7-silanorbornadiene (7) rearranges into a benzene derivative by formation of an SiO bond and 1,3-migration of the trimethylstannyl group. All products were characterised in solution by multinuclear magnetic resonance (¹H-, ¹¹B-, ¹³C-, ²⁹Si-, ¹¹⁹Sn-NMR spectroscopy). The geometries of 1,4,7,7-tetramethyl-7-silanorbornadiene, -7-silanobornene, and -7-silanorbornane were optimised by ab initio MO calculations (RHF/6-311+G(d,p) and chemical shifts δ²⁹Si were calculated (GIAO-RHF/6-311+G(d,p)).     

X-ray crystallographic investigation of the adduct of decachloro-o-carborane with dimethyl sulfoxide

Conclusions The structure of the 11 adduct of decachloro-o-carborane with DMSO was determined by x-ray crystallography. It was established that the structure contains cyclic associates of two DMSO molecules and two decachloro-o-carborane molecules linked by hydrogen bonds of the C-H...O type.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2257–2261, October, 1982.     

Reactions of azoesters and dimethyl acetylenedicarboxylate with 3-methyl-1,2,4-triazole-5-thione

The addition of dimethyl acetylenedicarboxylate to 3-methyl-1,2,4-triazole-5-thione ( 1 ), both in alcoholic medium and in inert solvents, has been investigated. When 1 was allowed to react with diethyl azodicarboxylate a disulfide 5 was obtained.     

Reaction of Δ3-pyrrolines with dimethyl acetylenedicarboxylate. A novel pyrrole forming rearrangement

Reaction of arylidene imines of methyl phenylglycinate with 2 moles of dimethyl acetylenedicarboxylate (ADE) leads, via an intermediate Δ³-pyrroline, to loss of the original methyl phenylglycinate moiety and formation of 2-aryl-3,4,5-tricarbo methoxypyrroles.     

Reaction of arylamidoximes with dimethyl acetylenedicarboxylate and diethyl chlorofumarate. Stereochemistry of the adducts and the derived 1,2,4-oxadiazines

It was shown that the addition of benzamidoxime to dimethyl acetylenedicarboxylate was predominantly cis-oid in methanol or acetonitrile solution and mainly trans-oid when benzene was the solvent. The stereochemistry of the cis-oid ( 4a ) and trans-oid ( 5 ) adducts was deduced by transformation into the oxadia-zinones ( 7a and 8a ) which, upon hydrolysis and subsequent reaction with acetic anhydride, gave the furo-[2,3-c]-1,2,4-oxadiazine ( 9 ) and the symmetrical anhydride ( 10 ), respectively. The reaction of diethyl chlorofumarate with the sodium salt of benzamidoxime produced the oxadiazinone ( 8c ).     

Metabolic products of microorganisms. An unexpected rearrangement in the chlorothricin series]

The O-methyl derivative II of chlorothricin aglycone is rearranged by alcoholic sodium hydroxide to the dihydronaphthaline III. The structure of the product is proven by spectroscopic investigations, dehydrogenation to the naphthaline derivatives VI and VIII, and by a spectroscopic comparison (UV., ¹H- and ¹³C-NMR.) with the synthetic analogues XXVII and XXVIII resp. The synthesis of the latter two compounds is described.     

Reactions of dimethyl acetylenedicarboxylate—VI : Reaction with aldehyde and ketone phenylhydrazones

Benzaldehyde phenylhydrazone with dimethyl acetylenedicarboxylate gives dimethyl 1,3-diphenylpyrazoline-4,5-dicarboxylate, dimethyl 1,3-diphenylpyrazole-4,5-dicarboxylate and trimethyl 1-phenylpyrazole-3,4,5-tricarboxylate; p-chlorobenzaldehyde phenylhydrazone gives trimethyl 1-phenyl-3,4,5-tricarboxylate and 1,2-(bis-phenylazo)-1,2-di-p-chlorophenylethane. Under similar conditions, p-tolualdehyde phenylhydrazone gives only trimethyl 1-phenylpyrazole-3,4,5- tricarboxylate. Acetophenone phenylhydrazone with dimethyl acetylenedicarboxylate gives dimethyl 1,3-diphenylpyrazole-4,5-dicarboxylate. Benzophenone phenylhydrazone, on the other hand, gives a mixture of dimethyl 1,3-diphenylpyrazoline-4,5-dicarboxylate and dimethyl 1,3-diphenylpyrazole-4,5- dicarboxylate. Benzyl methyl ketone and dimethyl acetylenedicarboxylate gives an enamine maleate, which is the Michael addition product.     

Reaction of 2-(5-aminopyrazol-1-yl)quinoxaline 4-oxides with dimethyl acetylenedicarboxylate

The reaction of 6-chloro-2-hydrazinoquinoxaline 4-oxide 6 with ethyl 2-(ethoxymethylene)-2-cyanoacetate or (1-ethoxyethylidene)malononitrile gave 2-(5-amino-4-ethoxycarbonylpyrazol-1-yl)-6-chloroquinoxaline 4-oxide 7a or 2-(5-amino-4-cyano-3-methylpyrazol-1-yl)-6-chloroquinoxaline 4-oxide 7b , respectively. The reaction of compound 7a or 7b with dimethyl acetylenedicarboxylate resulted in the 1,3-dipolar cycloaddition reaction and then ring transformation to afford 4-(5-amino-4-ethoxycarbonylpyrazol-1-yl)-8-chloro-1,2,3-trismethoxycarbonylpyrrolo[1,2-α]quinoxaline 8a or 4-(5-amino-4-cyano-3-methylpyrazol-1-yl)-8-chloro-1,2,3-trismethoxycarbonylpyrrolo[1,2-α]quinoxaline 8b , respectively.     

X-ray crystallographic and solution studies of the pentamethyldiethylenetriamine and tetramethylethylenediamine adducts of lithium diphenylphosphide

X-ray crystallographic studies on the lithium diphenylphosphide adducts (Me₂NCH₂CH₂)₂NMe₂ · LiPPh₂ (1) and Me₂NCH₂CH₂NMe₂ · LiPPh₂ (2) are reported.1 is monomeric, with a terminal PPh₂ unit containing a pyramidally coordinated phosphorus atom attached to the four-coordinate metal atom by a Li-P bond of length 2.567(6)Å.2 crystallizes as dimers, (Me₂NCH₂CH₂NMe₂ · LiPPh₂)₂, with bridging PPh₂ units containing (distorted) tetrahedrally coordinated phosphorus atoms: their planar (LiP)₂ rings are roughly square-shaped (mean PLiP angle 91°, mean LiP distance 2.61Å). Discussion of features of these structures is facilitated by ab initio MO calculations on the model systems LiPH₂ and (LiPH₂)₂. Cryoscopic molecular mass measurements and high-field⁷Li/³¹P NMR spectroscopic studies on solutions of1 and2 indicate that both solid-state structures are retained in arene solution, though some dissociation of2 into monomers is apparent.     

Cyclocondensation of amidines with dimethyl acetylenedicarboxylate: A convenient entry into tetramic acids

Amidines undergo cyclocondensations with dimethyl acetylenedicarboxylate (DMAD) to give highly functionalized 5‐dialkylamino‐4‐pyrrolin‐3‐ones. The products are crystalline, highly colored compounds that are uniquely functionalized and represent advanced intermediates in the construction of several other heterocyles, in particular the biologically active tetramic acids. The synthetic transformations of these compounds to tetramic acids are also described.     

Ring-opening polymerization of cyclobutane adducts of tetracyanoethylene and vinyl ethers with tertiary amines

Ring-opening polymerizations of cyclobutane adducts of tetracyanoethylene (TCNE) and vinyl ethers (VE) or p-methoxystyrene with tertiary amines are described. The polymerization of the cyclobutane adduct 1a of TCNE and ethyl vinyl ether (EVE) was carried out with 10 mol % of triethylamine in acetonitrile at ambient temperature to afford the alternating copolymer of TCNE and EVE with high molecular weight in good yield under various conditions. Under the optimum condition, the cyclobutane adducts of TCNE and a variety of VEs such as n-butyl vinyl ether, isobutyl vinyl ether, 2,3-dihydrofuran, and 3,4-dihydro-2H-pyran were polymerized to yield similar polymers. Although the cyclobutane adduct 4 of TCNE and p-methoxystyrene did not polymerize under these conditions, the treatment of 4 with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in acetonitrile at 60°C gave the polymer. On the basis of the fact that the polymer molecular weight increased rapidly at the initial stage and slowly even after the consumption of all of monomers, we propose that the tertiary amine initiates the chain anionic polymerization of the cyclobutane adduct to afford an ammonium macrozwitterion 3 , which is subjected to the intermolecular nucleophilic substitution with each other in a step polymerization manner. © 1995 John Wiley & Sons, Inc.     

Aryl- and aryloxyfurans as components of the diene synthesis with dimethyl acetylenedicarboxylate

The diene synthesis of 2-aryl- and 2-aryloxyfurans with dimethyl acetylenedicarboxylate gives adducts, the aromatizatio of which under the influence of acetic acid leads to esters of 3-aryl- and 3-aryloxy-6-hydroxyphthalic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 17–20, January, 1979.     

Thermal cycloadditions of dimethyl acetylenedicarboxylate with cyclic enolethers. An entry into medium size oxocyclic systems

Thermal cycloaddition of dimethyl acetylenedicarboxylate with a series of cyclic enolethers gave the corresponding bicyclic compounds which were expanded to medium size oxocyclic systems by further thermolysis or Lewis acid catalysis.     

A quantum chemical study on the reaction of 1-aryl-1,2-dihydrophosphinine oxides with dimethyl acetylenedicarboxylate

A β-oxophosphorane/ylide (2a) and an oxaphosphete (3a), the product and the possible intermediate of an inverse Wittig type reaction of 1-(2,4,6-triisopropylphenyl-)1,2-dihydrophosphinine oxide with dimethyl acetylenedicarboxylate were studied by quantum chemical calculations. The reaction of the title reagents following either a traditional [4 + 2] cycloaddition protocol to afford phosphabicyclo[2.2.2]octadiene 5 or a novel route yielding eventually β-oxophosphorane/ylide 2 was evaluated by energy calculations. The mechanism for the formation of intermediate 3a₂ was refined by HF/6-31G* transition state calculations. Analysis of the HOMO-LUMO orbitals of the reagents justified the reactivity experienced.     

Synthesis of 1,4-thiazino- and benzo-1,4-thiazinomorphinans: their acid-catalyzed rearrangement and study of the formation of unexpected oxidation products

The formation of 1,4-thiazine and benzo-1,4-thiazine rings was performed at the 6,7-positions of the morphinan backbone in order to synthesize systems annulated with a new six-membered ring providing potential pharmacological activity and the opportunity of easy functionalization. An unexpected oxidation of cyclic sulfur was observed in both cases affording either sulfones or open-ringed bis-morphinan-type by-product. These phenomena are in conformity with the observations and mechanistic explanations made by several research groups in the past in connection with the photosensitized oxidation of cyclic sulfides.     

Heavier alkali metal complexes of 2-phenylamidopyridine: an X-ray crystallographic and theoretical study of a structurally diverse series of crown ether adducts

Complexes of the anion of the secondary amine 2-phenylaminopyridine (LH) with the heavier alkali metals Na-Cs have been prepared in the presence of various macrocyclic polyether crowns [12-crown-4 (12C4), 15-crown-5 (15C5), and 18-crown-6 (18C6)], which coordinate to the metal ions in all cases. Depending on the combination of alkali metal and crown, the products include separated ion pairs [(crown)(2)M](+)L(-)(12C4/Na, 15C5/K, 15C5/Rb, 15C5/Cs) and contact-ion-pair neutral molecules [(crown)ML](15C5/Na, 18C6/Na, 18C6/K, 18C6/Rb) in which L(-) acts as a bidentate ligand. [((12C4)KL)(2)] is a dimer in which the amido and pyridine N atoms of two ligands bridge the metal ions, while [((18C6)KL(2)K)([infinity])] is a chain polymer with crown O and pyridyl N atoms acting as bridges in corner-sharing KOKN four-membered rings and may be regarded as a potassium potassate complex. [((18C6)Cs(2)L(2))([infinity])] is also polymeric, with a basic arrangement like that of [((12C4)KL)(2)], but with each 18C6 ligand mu-kappa6:kappa6 to two metal centres, generating the polymer. Although most of the [(crown)(2)M](+) sandwich cations have essentially parallel crown ligands, [(12C4)(2)Rb](+) is markedly bent, both in the complex incorporating THF as an additional ligand and in the THF-free complex, where two of these cations form a centrosymmetric dimer through two bridging oxygen atoms; DFT calculations indicate that the bending is inherent, thus enabling the coordination by an extra oxygen atom rather than being a consequence of this coordination. Attempts to isolate the caesium 12C4 derivative were unsuccessful. The compounds have been characterized by NMR spectroscopy, CHN microanalysis and, in most cases, X-ray crystallography.