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.     

A new synthesis of 3-hydroxy-2,3-dihydro-1,4-benzodioxin-2-carboxamides and 3-aminomethylene-1,4-benzodioxin-2(3H)-one derivatives

The 1,4-benzodioxin-2-carboxylic esters or carboxamides react with nucleophilic amines to give access to 3-hydroxy-2,3-dihydro-1,4-benzodioxin-2-carboxamides and 3-aminomethyn-1,4-benzodioxin-2(3H)-one precursors of potential therapeutical compounds. The basic environment (K₂CO₃ or amine) facilitates the process.     

Brønsted acid-catalyzed radical CH functionalization of acetone with N-allyl anilines to give 3-(3-oxobutyl)indolines

K₂S₂O₈ was unprecedentedly used instead of tert-butyl hydroperoxide (TBHP) in Brønsted acid-assisted catalytic strategy for ketonic radical generation, and the first Brønsted acid-catalyzed radical CH functionalization of acetone across unactivated alkenes is presented. In the presence of TsOH and K₂S₂O₈, N-allyl anilines underwent addition/cyclization cascade with acetone to afford 3-(3-oxobutyl)indolines with exo-selectivity and broad substrate scope at a relatively low temperature.     

Enantioselective Syntheses of α-Amino Acids from 10-(Aminosulfonyl)-2-bornyl Esters and Di(tert-butyl) Azodicarboxylate. Preliminary Communication

Succesive treatment of chiral esters 1 with LiN(i-Pr)₂/Me₃SiCl and di(tert-butyl) azodicarboxylate/TiCl₄/Ti(i-PrO)₄ gave N,N′ -di[(tert-butoxy)carbonyl]hydrazino esters 9 which on deacylation, hydrogenolysis, transesterification, and acidic hydrolysis furnished (2S)-α-amino acids 6 in high enantiomeric purity with efficient recovery of the auxiliary alcohol 7 .     

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.     

The first stable examples of compounds containing both diazonium and acyl azide,and synthesis of a new pyrazino[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazin-4(6H)-one heterocyclic system

The first stable compound containing both N₂⁺BF₄^? and CON₃ functional groups – 8-azidocarbonyl-3-(tert-butyl)-4-oxo-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-7-diazonium tetrafluoroborate was synthesized, and its stability and reactivity discussed. The Curtius rearrangement of 7-azido-3-(tert-butyl)-4-oxo-4,6-dihydropyrazolo[5,1-c][1,2,4]triazine-8-carbonylazide was investigated, and the synthesis of a novel heterocyclic system –pyrazino[2′,3′:3,4]pyrazolo[5,1-c][1,2,4]triazin-4(6H)-one is described.     

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.     

Synthesis of substituted 4-(3-alkyl-1,2,4-oxadiazol-5-ylmethyl)-3,4-dihydro-2H-1,4-benzoxazines and 4-(1H-benzimidazol-2-ylmethyl)-3,4-dihydro-2H-1,4-benzoxazines

Substituted 2H-1,4-benzoxazines were synthesized from substituted 2-amino phenols and 1,2-dibromoethane using K₂CO₃ in good to excellent yields. The cyclized products were further reacted with alkyl bromides to obtain the desired N-substituted 3,4-dihydro-2H-1,4-benzoxazines.     

Iodine-catalyzed synthesis of 2-arylpyrazolo[5,1-b]quinazolin-9(3H)-one derivatives in ionic liquids via domino reaction

The domino reaction of (E)-2-amino-N′-(1-arylethylidene)benzohydrazide and triethyl orthoformate in ionic liquids catalyzed by 10 mol % iodine gave 3a,4-dihydro-2-arylpyrazolo[5,1-b]quinazolin-9(3H)-one derivatives unexpectedly. In the presence of K₂S₂O₈, it could be oxidized to aromatized products in good yields.     

Di(tert-butyl)diazomethan: Thermische Zersetzung und Einelektronen-Redox-Reaktionen

Di(tert-butyl)diazomethane: Thermal Decomposition and One-Electron Redox Reactions. Di(tert-butyl)diazomethane is a potential precursor for the still unknown, presumably sterically overcrowded tetrakis(tert-butyl)ethane and, therefore, re-investigated. Its (Hel) photoelectron spectrum exhibits a low first vertical ionization energy of only 7.45 eV. Based on the ionization pattern, both the thermal decomposition above 600 K under nearly unimolecular conditions as well as the N₂ elimination at the surface of contacts, [Ni_x/C]_∞, [Rh₄(CO)₁₂/SiO₂]_∞, [Rh_x/SiO₂]_∞, and [Ag₂CO₃]_∞ are analyzed in a flow-system. Heterogeneously catalyzed, N₂ is split off already at room temperature, but in contrast to results for sterically less shielded diazo compounds, no dimer is formed, and only mixtures of known di(tert-butyl)carbene-isomerization products are isolated. Cyclic voltammetry at 233 K using a glassy carbon electrode proves a reversible oxidation followed by N₂ elimination at higher temperatures and an irreversible reduction. On chemical oxidation, however, no paramagnetic species can be detected, whereas chemical reduction at a potassium metal mirror in a THF solution containing (2.2.2)cryptand, yields the radical anion characterized by ESR spectroscopy. Without a cation-chelating ligand, the radical anion of a hitherto unknown dimer, ((CH₃)₃C)₂C?N? N?N? N?C(C(CH₃)₃) ₂' ^?, is generated, which dissociates at higher temperature, forming ((CH₃)₃C)₂?N₂' ^?. This one-electron reduction product of di(tert-butyl)diazomethane can also be detected after quickly warming up a solution containing presumably the radical anion of the triphenylphosphane adduct ((CH₃)₃C)₂C?N? N? PPh₃' ^?. In one of these reduction reactions, a N₂ elimination is observed.     

Silicon-carbon unsaturated compounds. 73. Photolysis of cis- and trans-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclohexane in the presence of tert-butyl alcohol and acetone

Irradiation of cis-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclohexane (1a) in the presence of tert-butyl alcohol in hexane with a low-pressure mercury lamp bearing a Vycor filter proceeded with high stereospecificity to give cis-2,3-benzo-1-tert-butoxy-1,4-dimethyl-4-phenyl-1,4-disilacyclooct-2-ene (2a), in 33% isolated yield, together with a 15% yield of 1-[(tert-butoxy)methylphenylsilyl]-4-(methylphenylsilyl)butane (3). The photolysis of trans-1,2-dimethyl-1,2-diphenyl-1,2-disilacyclohexane (1b) with tert-butyl alcohol under the same conditions gave stereospecifically trans-2,3-benzo-1-tert-butoxy-1,4-dimethyl-4-phenyl-1,4-disilacyclooct-2-ene (2b) in 41% isolated yield, along with a 12% yield of 3. Similar photolysis of 1a and 1b with tert-butyl alcohol-d₁ produced 2a and 2b, respectively, in addition to 1-[(tert-butoxy)(monodeuteriomethyl)(phenyl)silyl]-4-(methylphenylsilyl)butane. When 1a and 1b were photolyzed with acetone in a hexane solution, cis- and trans-2,3-benzo-1-isopropoxy-1,4-dimethyl-4-phenyl-1,4-disilacyclooct-2-ene (4a and 4b) were obtained in 25% and 23% isolated yield. In both photolyses, 1-(hydroxymethylphenylsilyl)-4-(methylphenylsilyl)butane (5) was also isolated in 4% and 5% yield, respectively. The photolysis of 1a with acetone-d₆ under the same conditions gave 4a-d₆ and 5-d₁ in 18% and 4% yields.     

Synthesis of 3-alkoxycarbonylaminomethylcarbonylamino-4-benzoyl-1,2-dihydropyridines and their cyclization to 5-phenyl-1,3,8,9-tetrahydro-2H-pyrido[3,4-e]-1,4-diazepin-2-ones

The regiospecific reaction of 3-benzyloxycarbonylaminomethylcarbonylamino-4-benzoylpyridine (6a) , or 3-t-butoxycarbonylaminomethylcarbonylamino-4-benzoylpyridine (6b) , with either acetyl chloride or ethyl chloroformate, and either n-butylmagnesium chloride or phenylmagnesium bromide afforded the respective 1-acetyl (or ethoxycarbonyl)-2-n-butyl (or phenyl)-3-benzyloxy (or t-butoxy) carbonylaminomethylcarbonylami-no-4-benzoyl-1,2-dihydropyridines 7 in 60-75% yield. Reaction of 1-acetyl (or ethoxycarbonyl)-2-n-butyl (or phenyl)-3-t-butoxycarbonylaminomethylcarbonyl-4-benzoyl-1,2-dihydropyridines 7b, 7f, 7d, 7h with trifluoroacetic acid gave the corresponding 5-phenyl-8-acetyl (or ethoxycarbonyl)-9-n-butyl (or phenyl)-1,3,8,9-tetrahydro-2H-pyrido[3,4-e]-1,4-diazepin-2-ones 8a, 8b, 8c, 8d respectively in 45–63% yield. N¹-Methylation of 5-phenyl-8-acetyl-9-n-butyl (or phenyl)-1,3,8,9-tetrahydro-2H-pyrido[3,4-e]-1,4-diazepin-2-ones 8a, 8b using sodium hydride and iodomethane yielded the corresponding N¹-methyl derivatives 9a (48%) and 9b (54%). Oxidation of 5,9-diphenyl-8-ethoxycarbonyl-1,3,8,9-tetrahydro-2H-pyrido[3,4-e]-1,4-diazepin-2-one (8d) using p-chloranil afforded 1,3-dihydro-5,9-diphenyl-2H-pyrido[3,4-e]-1,4-diazepin-2-one (10) . 5-Phenyl-8-acetyl-9-n-butyl-1,3,8,9-tetrahydro-2H-pyrido[3,4-e]-1,4-diazepin-2-one (8a) and the corresponding 8-ethoxycarbonyl analog 8c exhibited weak anticonvulsant activity indicating that 8a and 8c may be acting at the same site as the 7-halo-1,4-benzodiazepin-2-one class of compounds.     

New approach to the synthesis of tetrazole-containing buta-1,3-diynes: The total synthesis of 1,4-bis(2-(tert-butyl)-2H-tetrazol-5-yl)buta-1,3-diyne

An approach for the total synthesis of 1,4-bis(2-(tert-butyl)-2H-tetrazol-5-yl)buta-1,3-diyne was reported. Developed approach to the synthesis of 1,4-bis(2-(tert-butyl)-2H-tetrazol-5-yl)buta-1,3-diyne can be used for obtaining different 2,5-bis(tetrazol-5-yl)-disubstituted five-membered heterocycles (e.g. thiophenes, pyrroles, furans etc.), as well as tetrazole-containing monomers for the synthesis of new types of electroconductive and high energetic polymers.     

Enzymatic desymmetrization of 2-amino-2-methyl-1,3-propanediol: asymmetric synthesis of (S)-N-Boc-N,O-isopropylidene-α-methylserinal and (4R)-methyl-4-[2-(thiophen-2-yl)ethyl]oxazolidin-2-one

We report herein, the novel enzymatic desymmetrization of 2-tert-butoxycarbonylamino-2-methyl-1,3-propanediol 1. This method makes it possible to prepare (S)-N-Boc-N,O-isopropylidene-α-methylserinal 3, which is a chiral building block for the synthesis of a variety of α-substituted alanine derivatives. Moreover, optically active (4R)-methyl-4-[2-(thiophen-2-yl)ethyl]oxazolidin-2-one 4, one of the key intermediates in the synthesis of a novel immunosuppressant, has been prepared by this methodology.     

The Reactions of 6-(tert-Butyl)-3-hydrazino-1,2,4-triazin-5(2H)-one with Carbonyl Compounds

The reaction of 6-(tert-butyl)-3-hydrazino-1,2,4-triazin-5(2H)-one with acetone and benzaldehyde yields the corresponding hydrazones. In the presence of thionyl chloride the benzaldehyde hydrazone is converted to 3-(tert-butyl)-6-phenyl-1,2,4-triazolo[4,3-b]-1,2,4-triazin-2(1H)-one and this can also be formed via the acylation of the starting hydrazinotriazinone using benzoyl chloride.     

Element-Element-Bindungen. I. Synthese und Struktur des Tetra(tert-butyl)tetrarsetans und des Tetra(tert-butyl)tetrastibetans

Element-Element Bonds. I. Syntheses and Structure of Tetra(tert-butyl)tetrarsetane and of Tetra(tert-butyl)tetrastibetane Dilithium (tert-butyl)arsenide reacts with (tert-butyl)dichloroarsine to give tetra-(tert-butyl)tetrarsetane 1 ; homologous tetra(tert-butyl)tetrastibetane 2 is formed by reduction of (tert-butyl)dichlorostibane with magnesium. The isotypic compounds 1/2 crystallize in the monoclinic space group P2₁/c with Z = 4. The dimensions of the unit cells determined at ?45 ± 5°C are: a = 957.4(8)/1 000.2(3); b = 1 399.1(14)/1 423.9(4); c = 1 697.4(9)/1 749.8(7) pm; β = 96.02(6)/96.77(3)°. As shown by low temperature X-ray structure determinations (3 531/3 232 symmetry independent reflections; R_g = 4.0/4.6%) the four membered rings E₄ (E = As or Sb) are folded; in all-trans configuration the bulky organic substituents occupy pseudo-equatorial positions. Characteristic averaged bond distances and angles are: E? E 244/282; E? C 202/221 pm; ? E? E? E 86/85° ? E? E? C 101/99°. The dihedral angels of the bisphenoides built up by the atoms of the rings are found to be 139/133°.     

Solid state conformations of α,β-unsaturated hydroxamates derived from the ‘chiral Weinreb amide’ auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine

α,β-Unsaturated hydroxamates derived from the ‘chiral Weinreb amide’ auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-tert-butylhydroxylamine consistently adopt a defined conformation and undergo highly diastereoselective conjugate addition reactions with lithium amide reagents. The configuration of the N-1-(1′-naphthyl)ethyl group dictates the position of the O-tert-butyl group and also the configuration adopted by the pyramidal nitrogen atom via a ‘chiral relay’ effect. Conjugate addition of lithium amide reagents to these substrates proceeds on the face opposite to both the O-tert-butyl group and nitrogen lone-pair with high levels of diastereoselectivity.     

Influence of cobalt(III) dimethyldithiocarbamate complexes on styrene polymerization initiated by tert-butyl perbenzoate

Kinetic features of radical polymerization of styrene initiated by tert-butyl perbenzoate in the presence of tris(N,N-dimethyldithiocarbamato)cobalt(III) (CoL₃) and its adduct with iodine (CoL₃ · 2I₂) were studied. The optimal concentration ratios of the activators and tert-butyl perbenzoate, providing fast styrene polymerization at 338–368 K, were determined.     

Heterocyclization reactions of azinoisocyanates. Synthesis of 2H-1,2,4-triazol-3(4H)-one derivatives

The reaction of 1-aminoethylidenehydrazones 9 with di-tert-butyl dicarbonate and 4 -dimethylaminopyridine led to the corresponding azinoisocyanates 10 , which underwent thermal rearrangement under the reaction conditions to give 4-(tert-butoxycarbonyl)-5-methyl-2H-1,2,4-triazol-3(4H)-ones 14 . However, amidrazone 17 gave 2-(2-tert-butoxycarbonyloxy-2-phenyl)ethyl-4-(tert-butoxycarbonyl)-5-methyl-2H-1,2,4-triazol-3(4H)-one 22 and N-aziridinyliminocarbamate 18 under the similar conditions.     

New methodology for the preparation of N-tosyl aziridine-2-carboxylates

N-Tosyl aziridine-2-carboxylate methyl esters were prepared from methyl N-tosyl-l-serinate or N-tosyl-l-threoninate, tosyl chloride, and K₂CO₃, under phase-transfer catalysis (PTC) conditions. The same methodology, as applied to the tert-butyl N-tosyl-l-serine amide, afforded the corresponding newly prepared aziridine-2-carboxamide, as an enantiomerically pure compound.