Reaction of 3,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)-1,2-benzoquinone with terminal alkylacetylenes in the presence of phosphorus trichloride

A reaction of 3,6-di(tert-butyl)-1,2-benzoquinone with alkynes in the presence of phosphorus trichloride leads to a predominant formation of 4-alkyl- and 4-haloalkyl-5,8-di(tert-butyl)-2,6-dichloro-2 H- benzo[e][1,2]oxaphosphinine 2-oxide. An ipso-substitution of the tert-butyl group at ortho-position to the oxygen atom of the benzophosphinine system with the formation of 4-alkyl-5- tert-butyl-2,8-dichloro-2 H-benzo[e][1,2]oxaphosphinine 2-oxide was the minor route of the reaction with alkylacetylenes. Molecular structures of 4-butyl-5,8-di( tert-butyl)-2,6-dichloro-2 H- benzo[e][1,2]oxaphosphinine 2-oxide and 5,8-di( tert-butyl)-2,6-dichloro-4-hexyl-2 H-benzo[e][1,2]oxaphosphinine 2-oxide were studied by X-ray analysis.     

Reaction of 4,6-bis(tert-butyl)-2,2,2-trichlorobenzo[d]-1,3,2-dioxaphosphole with phenylacetylene. ipso-Substitution of the tert-butyl group

The reaction of 4,6-bis(tert-butyl)-2,2,2-trichlorobenzo[d]-1,3,2-dioxaphosphole with phenylacetylene follows the mechanism of ipso-substitution of the tert-butyl group that is in para-position relative to the endocyclic O atom of the heterocycle, predominantly yielding 8-(tert-butyl)-2,6-dichloro-2-oxo-4-phenylbenzo[e]-1,2-oxaphosphorinine (NMR data). The structure of its hydrolysis product, 8-(tert-butyl)-6-chloro-2-hydroxy-2-oxo-4-phenylbenzo[e]-1,2-oxaphosphorinine, was proved by X-ray diffraction analysis.     

Structure of the oxidative dimerization product of 4,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)pyrogallol

The structure of the oxidation product of 4,6-di(tert-butyl)pyrogallol, viz., 6,10a-dihydroxy-3,4a, 7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxine-1,2-dione, was established by X-ray diffraction. Dimerization of intermediate 3-hydroxy-4,6-di(tert-butyl)-1,2-benzoquinone occurs by the mechanism of Diels—Alder heterocyclization. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 267–271, February, 2007.     

Reactions of phenylenedioxytrihalophosphoranes with arylacetylenes. 5. Regiochemistry of the reaction of 2,2,2-trichloro-5-chlorocarbonylbenzo[d]-1,3,2-dioxaphosphole with phenylacetylene. Synthesis and three-dimensional structures of 6-alkylaminocarbonyl-2-oxo-4-phenylbenzo[e]-1,2-oxaphosphorinine derivatives

2,2,2-Trichloro-5-chlorocarbonylbenzo[d]-1,3,2-dioxaphosphole was prepared for the first time by the reaction of protocatechuic acid with phosphorus pentachloride or trichloride followed by chlorination. According to the results of NMR spectroscopy, the reaction of this phosphole with phenylacetylene gave rise to 2,5-dichloro- and 2,8-dichloro-6-chlorocarbonyl-2-oxo-4-phenylbenzo[e]-1,2-oxaphosphorinines as the major products. The molecular and supramolecular structures of their stable derivatives, viz., 2-tert-butylamino-6-tert-butylaminocarbonyl-5-chloro-2-oxo-4-phenylbenzo[e]-1,2-oxaphosphorinine and isopropylammonium 8-chloro-6-isopropylaminocarbonyl-2-oxo-4-phenylbenzo[e]-1,2-oxaphosphorinin-2-oate, respectively, were established by X-ray diffraction analysis.     

Ugi three-component coupling reaction for the synthesis of 2-(6-oxo-11-phenyl-7,8-dihydrobenzo[b]pyrrolo[1,2-d][1,4]diazocin-5(6H)-yl)-2-phenylacetamide derivatives

A three-component, four center Ugi reaction of 3-(1-(2-aminophenyl)-5-phenyl-1H-pyrrol-2-yl)propanoic acid with aromatic aldehyde and t-butyl isocyanide has been achieved to produce a novel class of N-tert-butyl-2-(6-oxo-11-phenyl-7,8-dihydrobenzo[b]pyrrolo[1,2-d][1,4]diazacine-5(6H)-yl)-2-phenylacetamides in moderate to good yields.     

Reversed steric order of reactivity for tert-butyl and adamantyl-3-cyanomethylene-1,2,4-triazines

Reactions of 2-(6-tert-butyl-5-oxo-4,5-dihydro-1,2,4-triazin-3(2H)-ylidene)-3-oxo-3-R-propanenitriles (R = t-Bu, Ad-1) with tert-butyl bromoacetate gave the corresponding N(2), C(5)O bis-alkylation products. Treatment of the latter with t-BuLi, in the case of R = t-Bu, led to intramolecular condensation at the exocyclic nitrile group. However, in the case of R = Ad-1, the condensation with the sterically more hindered carbonyl group was observed to give diastereomerically pure 8-cyanopyrrolo[1,2-b][1,2,4]triazine-6-carboxylate derivatives. The structures of the isolated products were confirmed by spectral methods and X-ray single-crystal diffraction.     

Synthesis of new halo-substituted pyrazolo[5,1-c][1,2,4]triazines

Ethyl 3-tert-butyl-4-oxo-7-X-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-8-carboxylates (X = H, Cl, Br) were synthesized for the first time by diazotization of 7-amino-3-tert-butyl-4oxo-8-ethoxycarbonyl-6H-pyrazolo[5,1-c][1,2,4]triazines with tert-butyl nitrite in the presence of trimethylsilyl halides. A new method was developed: a reaction between 7-amino-3-tert-butyl-4-oxo-6H-pyrazolo[5,1-c][1,2,4]triazine-8-carboxylic acid and I₂/TEA followed by treatment with NaBH₄ led to a mild decarboxylation. The acid reacts with N-halosuccinimides to give novel 8-halo-substituted derivatives. The amino groups of the latter were acylated by treatment with trifluoroacetic anhydride to give monoacylation products.

     

Bromination regiochemistry of 4-Phenyl-2,7-dichloro-2H-chryseno-[6,5-e][1,2]phosphinine 2-oxide

Regioselective bromination of 4-phenyl-2,7-dichloro-2H-chryseno[6,5-e][1,2]phosphinine 2-oxide proceeded in the position 3 with the formation of 3-bromo-4-phenyl-2,7-dichloro-2H-chryseno[6,5-e][1,2] phosphinine 2-oxide; the structure of its 2-tert-butylamino derivative was established by XRD analysis and correlation spectroscopy.     

A reaction of 3,6-di(tert-butyl)-4-chloro-1,2-benzoquinone with potassium ethyl xanthate. New sulfur-containing o-quinones

In a reaction of 3,6-di(tert-butyl)-4-chloro-1,2-benzoquinone with potassium ethyl xanthate, the halogen atom was replaced by the ethyl xanthate group. Acid hydrolysis of the product gave 4,7-di(tert-butyl)-5,6-dihydroxy-1,3-benzodithiol-2-one containing a pyrocatechol fragment, which was oxidized into the corresponding quinone. When irradiated in solution with visible light, this quinone quantitatively eliminated a CO molecule with contraction of the ring to a five-membered one. The quinones obtained were studied as ligands in coordination spheres of metals by ESR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 683–686, April, 2006.     

Heterocyclic analogs of 5,12-naphthacenequinone 8.* Synthesis of furano-anthraquinones

During the condensation of 2,3-dichloroquinizarine with methyl pivaloylacetate in the presence of potassium carbonate in dimethyl sulfoxide the main reaction products are derivatives of angular 3-pivaloylanthra[1,2-b]furan-2,6,11(3H)-trione (about 70%) and anthra[2,1-d][1,3]dioxole-6,11-dione (15%), whereas the yield of the targeted linear methyl 2-tert-butyl-4,11-dihydroxyanthra[2,3-b]furan-5,10-dione-3-carboxylate is only 2%. Methods are developed for modification of the obtained 3-pivaloylanthra[1,2-b]furan-2,6,11(3H)-trione, making it possible to use it for the synthesis of the tert-butyl derivatives of linear anthra[2,3-b]furan-5,10-dione or angular anthra[1,2-b]furan-6,11-dione. *For Communication 7 see [1]. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 191–202, February, 2009.     

Structure,synthesis, and voltammetric investigation of 1-(quinolin-2-yl)-2-(pyran-2-yl)ethane-1,2-dione derivatives

By the XRD analysis the structure was established of 1-(7,8-dimethyl-4-chloroquinolin-2-yl)-2-[3,5-di(tert-butyl)-6-oxo-6H-pyran-2-yl]ethane-1,2-dione formed as a result of the oxidation of 3,5-di(tert-butyl)-6-[(Z)-2-(quinolin-2-yl)-1-hydroxyethen-1-yl]pyran-2-ones. By the cyclic voltammetry the oxidation of 1-(quinolin-2-yl)-2-(pyran-2-yl)ethane-1,2-dione derivatives was shown to proceed in two stages.     

Synthesis of substituted 7,8-di(propylsulfonyl)pyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrazines

Heating of pyrazinium salts with E-1,2-dichloro-1,2-di(propylsulfonyl)ethene in chloro-form in the presence of three-fold excess of Et₃N regiospecifically gives rise to substituted 7,8-di(propylsulfonyl)pyrrolo[1,2-a]pyrazines in high yields. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 424–426, February, 2008.     

Regio-selective synthesis of novel 1-tert-butyl-4-nitro-1H-pyrrole-3-carboxylic acid building block

A convenient, regio-selective synthesis of novel 1-tert-butyl-4-nitro-1H-pyrrole-3-carboxylic acid was developed, utilizing the bulky tert-butyl moiety of 1-tert-butyl-1H-pyrrole to direct selective, un-symmetrical substitutions to the desired 3 and 4 positions.     

Synthesis and molecular structure of 3-[5-(quinolin-2-yl)penta-1,4-dien-1-yl]-1,4-benzodioxin-2-one

Acid-catalyzed reaction of 6,10a-dihydroxy-3,4a,7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo-[b,e][1,4]dioxine-1,2-dione with 4-chloro-2,7,8-trimethylquinoline gave previously unknown 3,6,8-tri-tert-butyl-3-[2-tert-butyl-5-(4-chloro-7,8-dimethylquinolin-2-yl)-4-hydroxy-3-oxopenta-1,4-dien-1-yl]-5-hydroxy-1,4-benzodioxin-2-one whose structure was determined by X-ray analysis. The energy and structure parameters of possible isomers of the product in the gas phase and in solution were estimated by PBE0/6-31G** quantum-chemical calculations.     

3-Hydrazino-1,2,4-triazin-5(2H)-ones in Reactions with Compounds Containing Carbonyl and Active Methylene Groups

Boiling of ethyl cyanoacetate with 6-tert-butyl-3-hydrazino-1'2'4-triazin-5(2H)-one in alkalinemedium yielded 6-tert-butyl-3-(5-hydroxy-3-oxo-2'3-dihydro-1H-pyrazol-1-yl)-1'2'4-triazin-5(2H)-one.Acylation of 6-tert-butyl-3-hydrazino-1'2'4-triazin-5(2H)-one with benzoyl chloride furnished 3-benzoyl-hydrazido-1'2'4-triazine that cyclized when treated with POCl₃ providing a derivative of[1'2'4]triazolo[4'3-b][1'2'4]triazine. Boiling of 6-tert-butyl-3-hydrazino-1'2'4-triazin-5(2H)-one in glacialacetic acid gave rise to diacetylated derivative whereas the boiling with acetic anhydride in an inert solventafforded monoacetylated product.     

Intramolecular Schmidt reaction of tert-butyl 3-(3-azidopropyl)-4-oxopiperidine-1-carboxylate as a synthetic route to saturated fused aza heterocycles

Treatment of the title compound with trifluoroacetic acid induced intramolecular Schmidt reaction with formation of a saturated fused heterocyclic system, tert-butyl 5-oxo-2,3,4,5,7,8,9,9a-octahydro-1H-pyrrolo[1,2-a][1,4]-diazepine-2-carboxylate. The latter was reduced with lithium tetrahydridoaluminate, and subsequent treatment with hydrogen chloride in dioxane gave 2,3,4,5,7,8,9,9a-octahydro-1H-pyrrolo[1,2-a][1,4]-diazepine dihydrochloride which is a promising intermediate product for the synthesis of N-substituted diazepines with a fused pyrrole ring.     

Synthesis and molecular structure of 7<Emphasis Type="Italic">H</Emphasis>-12-oxa-3,7-diazapleiadene-substituted 1,3-tropolones

An acid-catalyzed reaction of substituted 2-methyl-7H-12-oxa-3,7-diazapleiadenes with 1,2-benzoquinones leads to 7H-12-oxa-3,7-diazapleiadene-substituted 1,3-tropolones. Molecular structure of 5,7-di(tert-butyl)-2-[9,11-di(tert-butyl)-4-methyl-7H-12-oxa-3,7-diazapleiaden-2-yl]-4-nitro-1,3-tropolone was established by X-ray crystallography. Energy and structural characteristics of isomeric 5,7-di(tert-butyl)-2-[9,11-di(tert-butyl)-4-methyl-7H-12-oxa-3,7-diazapleiaden-2-yl]-4-nitro-1,3-tropolones in the gaseous phase and a polar solution were studied by the PBE0/6-31G** method.     

Photoinitiated processes in 1-p-tolylsulfonylazo-2,4,6,8-tetrakis(tert-butyl)phenoxazine

New photochromic compound 1-p-tolylsulfonylazo-2,4,6,8-tetrakis(tert-butyl)phenoxazine containing the intramolecular hydrogen bond NH...N and the corresponding model structures 2,4,6,8-tetrakis(tert-butyl)-1-(veratroylazo)phenoxazine and 2,4,6,8-tetrakis(tert-butyl)-N-acetyl-1-(p-tolylsulfonylazo)phenoxazine were synthesized and studied. The data obtained suggested the mechanism of the photoreaction resulting in the accumulation of betaine 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)-10-tolylsulfonylphenoxazin-9-one. The photochromic transformations in the molecule under study are due to intramolecular proton phototransfer followed by E–Z-isomerization about the N–N bond and the formation of betaine 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)-10-tolylsulfonylphenoxazin-9-one. The molecular and crystal structure of the photoproduct was studied by X-ray analysis.     

Synthesis of new fluorescent building blocks via the microwave-assisted annulation reaction of 1,1,2-trimethyl-1H-benzo[e]indole with acrylic acid and its derivatives

The reaction of 1,1,2-trimethyl-1H-benzo[e]indole with acrylic acid and its derivatives was employed for the preparation of novel fluorescent building blocks. Treatment of 1,1,2-trimethyl-1H-benzo[e]indole with acrylic acid, acrylamide or tert-butyl acrylate in an autoclave or a microwave reactor at 180–200 °C afforded benzo[e]pyrido[1,2-a]indole derivatives. Various chemical transformations of the latter compounds have been performed to yield functionalized benzo[e]indole scaffolds. The structure assignments were based on data from ¹H and ¹³C NMR spectroscopy and single crystal X-ray analyses. The optical properties of the obtained benzo[e]indoline derivatives were studied by UV–vis and fluorescence spectroscopy.     

Synthesis and structure of heterocyclic derivatives of pyran-2-ones based on the dimer of 4,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)-3-hydroxy-1,2-benzoquinone

Acid-catalyzed reaction of 6,10a-dihydroxy-3,4a,7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo-[b,e][1,4]dioxine-1,2-dione with 2-methylquinoline derivatives led to the formation of a previously unknown system 6-[(Z)-2-(quinolin-2-yl)-1-hydroxyethen-1-yl]pyran-2-one. The molecular structure of 3,5-di(tert-butyl)-6-[(Z)-2-(7,8-dimethyl-4-chloroquinolin-2-yl)-1-hydroxyvinyl]pyran-2-one was established by XRD method; the energy and structural characteristics of its isomers in the gas phase and in a polar solvent were calculated by quantumchemical methods (B3LYP/6-31G**).