Synthesis of 6,7-dihydro-5H-dibenzo[c,e]azepines and biaryls by palladium-catalyzed Ullmann reaction

A novel palladium-catalyzed Ullmann protocol is described for the synthesis of 6,7-dihydro-5H-dibenzo[c,e]azepines and biaryls. In the presence of Pd(OAc)₂ and KOAc, intramolecular or intermolecular Ullmann coupling of aryl halides proceeds efficiently under ligand-free and aerobic conditions to afford the corresponding 6,7-dihydro-5H-dibenzo[c,e]azepines and biaryls in moderate to excellent yields.     

Dimerization/Elimination of β-Styrylmalonates under Action of TiCl4

A new type of dimerization of dimethyl (β-styryl)malonates in the presence of TiCl₄ accompanied by elimination of a methanol molecule was discovered. Selective methods for the synthesis of substituted trimethyl 4-hydroxy-[1,1′-biaryl]-3,3,5(2H)-tricarboxylates and trimethyl 7-hydroxy-9,10-dihydro-5,9-methanobenzo[8]annulene-6,8,8(5H)-tricarboxylates were developed. The regularities of the occurring processes were determined and a similar reaction of β-styrylmalonate with benzylidenemalonate in the presence of TiCl₄ was performed in the scope of the suggested mechanism.     

Microwave-assisted synthesis of 4H-benzo[f]imidazo[1,4]diazepin-6-ones via a post-Ugi copper-catalyzed intramolecular Ullmann coupling

An efficient post-Ugi copper-catalyzed intramolecular Ullmann coupling strategy has been elaborated for the diversity-oriented synthesis of 4H-benzo[f]imidazo[1,4]diazepin-6-ones and the scope and limitations of this protocol are investigated.     

Photochemical formation of novel pyrrolo[3,2-b]-6,7-benzobicyclo[3.2.1]octa- 2,6-diene

The first synthesis of 1,4,9,10-tetrahydro-4,9-methanobenzo[4,5]cyclohepta[1,2-b]pyrrole (11) was achieved by the photochemical intramolecular [2 + 2] cycloaddition of N-phenoxycarbonyl- (5a) and N-ethoxycarbonyl-2-[2-(2-vinylphenyl)]pyrrole (6a), respectively, followed by basic hydrolysis of the isolated N-substituted 1,4,9,10-tetrahydro-4,9-methanobenzo[4,5]cyclohepta[1,2-b]pyrroles (10a, 10b). Some competitively formed products were also isolated.     

Copper-catalyzed coupling of (S)-1-(3-bromophenyl)-ethylamine and N-H containing heteroarenes using microwave heating

The Ullmann coupling of (S)-[1-(3-bromophenyl)-ethyl]-ethylamine (1) with a variety of N-H heteroarenes using microwave heating is described.     

An expedient approach to substituted triazolo[1,5-a][1,4]benzodiazepines via Cu-catalyzed tandem Ullmann C–N coupling/azide-alkyne cycloaddition

An approach to the synthesis of triazolo[1,5-a][1,4]benzodiazepines comprising copper catalyzed tandem Ullmann C–N coupling followed by azide-alkyne cycloaddition has been described. The reaction of o-azidobenzylbromide and N-propargylated aniline derivatives in the presence of CuI and base leads to the formation of triazolo[1,5-a][1,4]benzodiazepines. The reaction has been successfully generalized by synthesizing a number of triazolo[1,5-a][1,4]benzodiazepine derivatives in good to excellent yields.     

Theoretical estimation of the possibility of formation of oxadiazocines in the nucleophilic addition of resorcinol to pyrimidines and synthesis of new azoloannelated benzooxadiazocines

A method was proposed for estimating the possibility of cyclization of adducts of resorcinol with pyrimidines to form oxadiazocines based on the conformational criterion and analysis of charges on the C(5) atom of the pyrimidine ring and on the H atom of the hydroxy group of the resulting adducts. A series of new derivatives of 4,5-dihydro-11H-5,11-methanobenzo[g]azolo[1,3,5]oxadiazocines were synthesized. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1573–1577, August, 1999.     

Synthesis of dihydroindolizines for potential photoinduced work function alteration

Seeking to immobilize photochromophores on metallic surfaces, we have synthesized four molecules which contain both a photoresponsive dihydroindolizine (DHI) core and a sulfur containing moiety, which allow for their assembly onto gold substrates. Sonogashira, Suzuki, or Ullmann couplings are employed to generate pyridines with pendant thioacetates (or disulfides). The pyridines are condensed with spiro[2-cyclopropene-1,9′-[9H]fluorene]-2,3-dimethyl ester affording the targeted DHIs.     

Mild Method for Ullmann Reaction of 2‐Chlorobenzoic Acids and Aminothiazoles or Aminobenzothiazoles under Ultrasonic Irradiation

One‐pot syntheses of 5H‐[1,3]thiazolo[2,3‐b]quinazolin‐5‐one, 12H‐[1,3]benzothiazolo[2,3‐b]quinazolin‐12‐one, and corresponding derivatives were developed using the copper‐catalyzed Ullmann condensation. The use of ultrasonic irradiation enhanced yields and reduced the reaction time to minutes.     

Synthesis of imidazobenzothiazine and primidobenazothiazine derivatives via the classic Ullmann cross-coupling reaction of 1,8-diiodonaphthalene with 1H-benzo[d]imidazole-2-thiols or 2-thiouracils

A feasible protocol for the synthesis of imidazobenzothiazine and primidobenazothiazine derivatives via the classic copper(I)-catalyzed Ullmann cross-coupling process has been developed. 1,8-Diiodonaphthalene could couple with 2-mercaptobenzimidazoles or 2-thiouracils to give the corresponding benzo[4,5]imidazo[2,1-b]naphtho[1,8-de][1,3]thiazines and 11H-naphtho[1,8-de]pyrimido[2,1-b][1,3]thiazin-11-ones in moderate yields.     

Synthesis of purinobenzothiazine and pyridothiazinopurine derivatives. Two new heterocyclic ring systems

The synthesis of derivatives of two new heterocyclic systems, purino[8,7-b][1,3]benzothiazine and pyrido[3′,2′:5,6][1,3]thiazino[3,2-f]purine, was effected by the Ullmann reaction between 8-mercaptotheophylline or 8-bromotheophylline with the appriopriately substituted benzoic or nicotinic acid, respectively. The 8,8′-dithiobistheophylline is also reported.     

I-MCR-Ullmann cascade toward furo[2,3-b]indole scaffold

An efficient method for the construction of furo[2,3-b]indole derivatives 5 via an isocyanide-based multicomponent reaction (I-MCR) and a copper-catalyzed intramolecular Ullmann reaction sequence was described. This two-step sequence can be performed in a one-pot manner to produce the desired product 5 in moderate to good yield (up to 90%).     

Facile Synthesis of Nitrogen Tetradentate Ligands and Their Applications in CuI‐Catalyzed N‐Arylation and Azide–Alkyne Cycloaddition

Five new tetradentate ligands [NNNN] with benzimidazolyl‐imine or amine nitrogen donors have been synthesized in good yields under mild conditions from easily available substrates. trans‐N,N′‐bis(1‐Ethyl‐2‐benzimidazolylmethylene)cyclohexane‐1,2‐diimine is the best accelerating ligand in this series that supports the Cu^I‐catalyzed Ullmann N‐arylation and the direct three‐component azide–alkyne cycloaddition reaction to give the corresponding substituted imidazole, pyrazole, and triazole in high yields. Single‐crystal X‐ray diffraction analysis of its complex with CuI reveals a novel one‐dimensional coordination polymer of the metal chain bridged alternately by the [NNNN] ligand and diiodides.     

A mild and regioselective Ullmann reaction of indazoles with aryliodides in water

A mild and regioselective Ullmann reaction of indazoles with aryliodides has been developed as a general method for the synthesis of 1-aryl-1H-indazoles. Water was used as the solvent wherein Tween 20 (2% w/w) was added to form aqueous micelles to improve solubility of starting materials and accelerate reaction rate. This aqueous protocol allows the Ullmann reaction to proceed at a mild temperature (60 °C) within a short reaction time (2 h), which typically requires high temperatures (≥100 °C) and prolonged duration (≥24 h). The protocol demonstrated broad substrate scopes with good isolated yields and high regioselectivity (N-1 arylation over N-2 arylation) for 25 examples examined.     

Preparation of new dihydrofuro[2,3-f]indole derivatives

The preparation of new dihydrofuro[2, 3-f]indole derivatives and their fully aromatic counterparts is described. Key steps in the synthesis include a Claisen rearrangement/m-chloroperoxybenzoic acid oxidation sequence to form a dihydrobenzofuran intermediate and an iron/acetic acid reductive cyclization to generate the dihydrofuro[2, 3-f]indole nucleus. Introduction of a 5-phenyl substituent on the indole nitrogen was effected by a modified Ullmann reaction. Fully aromatic furo[2, 3-f]indoles were obtained from the dihydro congeners by dehydrogenation with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone.     

Copper(II) trans-bis-(glycinato): an efficient heterogeneous catalyst for cross coupling of phenols with aryl halides

Copper(II) trans-bis-(glycinato) complex, easily prepared by the solid state reaction of copper(II) acetate and glycine (trans-[Cu(glyo)₂·H₂O]) was found to be an efficient, recyclable, and high yielding catalyst for the Ullmann type synthesis of diaryl ethers via the cross coupling of phenols with aryl halides without using any additives at relatively low reaction temperature. The catalyst could easily be recovered by simple filtration and was reused for several runs with consistent catalytic activity.     

Cascade C?N and C?O bond constructions for the synthesis of dibenzoimidazo[1,4]oxazepines catalyzed by CuI/o-phen

A novel method for the synthesis of dibenzo[b,f]imidazo[1,2-d][1,4]oxazepine derivatives was described via cascade Csp² N and Csp² O bond constructions. It was a crossed double Ullmann reactions using 4,5-diaryl-2-(2-hydroxylphenyl)-1H-imidazole as the double nucleophilic centers in the presence of Cs₂CO₃, while 1-bromo-2-iodobenzene was used as a substrate catalyzed by CuI and o-phenanthroline in good yields.     

One‐Pot Ullmann C–N Coupling Cyclization Toward Domino Synthesis of Fused Hexacyclic Quinolinotriazoloacridinones Catalyzed by CuI/L‐Proline

A one‐pot method for consecutive Konoevenagel condensation, Michael addition, cyclization, dehydrogenation, and Ullmann coupling of 2‐halogenated aromatic aldehyde, 1H‐benzo[d ][1,2,3]triazol‐5‐amine, and cyclohexane‐1,3‐diones is presented. This procedure provided an efficient synthesis of fused hexacyclic quinolinotriazoloacridinone derivatives in good yields catalyzed by CuI/L‐proline.     

A new synthesis of anthyridine derivatives

An Ullmann reaction between 2-bromonicotinic acid and 2,6-diaminopyridine gave 6 -amino-2,2 -dipyridylamino-3-carboxylic acid (V). The latter was converted into 7-amino-5H-dipyrido-[1,2-a:2,3 -d]pyrimidin- 5-one (VII) by heating with polyphosphoric acid and into 2-amino-5,10 H-anthyridin-5-one (VIII) by heating with concentrated sulfuric acid. Structure proofs of VII and VIII are given and some derivatives of VIII are described.     

Synthesis and stereochemical resolution of functional [5]pericyclynes

Three different kinds of ring carbo-mers of [5]cyclitol ethers were targeted as challenging examples of functional [5]pericyclynes. Three tertiary pentaaryl-carbo-[5]cyclitol methyl ethers were synthesized through a [11+4] ring-closing double addition of triphenyl- and tri-p-anisyl-undecatetrayn-diides to dibenzoylacetylene. These compounds, obtained as oily mixtures of stereoisomers, are stable and can behave as acetylenic ligands of one or two Co₂(CO)₆ units. NMR analysis reveals that the broad diasteroisomeric dispersity of a triether, is consistently reduced in the symmetrized pentaether. Three bis-secondary triaryl-carbo-[5]cyclitol methyl ethers with adjacent CH(OR) vertices were synthesized through a similar [11+4] ring-closing process, where the same tetrayn-diides add to both the carbaldehyde ends of the (η²-OCH-CC-CHO)Co₂(CO)₆ complex. Despite the possibility of tautomeric isomerization, the occurrence of two adjacent bis-propargylic carbinol vertices does not diminish the stability of the [5]pericyclyne framework. Finally, two bis-secondary carbo-[5]cyclitol methyl ethers with non-adjacent CH(OH) vertices were synthesized through an alternative [10+5] ring-closing process. The bis-secondary carbo-[5]cyclitols are regarded as isohypsic equivalents of the challenging [C,C]₅carbo-cyclopentadienyl cation. A diphenyl-hexaoxy-[5]pericyclyne with two non-adjacent secondary carbinol vertices was also prepared through a [10+5] ring-closing strategy: this molecule is an isohypsic equivalent of the previously calculated zwitterionic carbo-cyclopentadienone, which could be observed as a DCI/NH₃-MS fragment after treatment with SnCl₂/HCl. Analytical HPLC showed that the C₁₁ triphenyl-undecatetrayne precursor of the [11+4] strategy was obtained as a statistical 1:2:1 mixture of the three possible diastereoisomers. Semi-preparative HPLC allowed for the resolution of this mixture. The pure major diastereoisomer was employed to prepare a partly resolved sample of pentamethoxy-pentaphenyl-[5]pericyclyne. Analytical HPLC showed that the latter corresponds to the statistical distribution of the expected three residual diastereoisomers. Semi-preparative HPLC finally afforded samples of diastereoisomerically pure pentamethoxy-[5]pericyclyne as crystalline solids.