Synthesis of some substituted 5,6,11,12-tetrahydro-dibenzo[a,e]cyclooctene derivatives through the intermediacy of tricarbonyl(η-arene)chromium complexes

5,6,11,12-Tetrahydrodibenzo[a,e]cyclooctene derivatives with α- and β-substituents are readily accessible from [Cr(CO)₃(5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene)] 2 via a two-step sequence, which involves addition of a nucleophile and oxidation of the intermediate anionic cyclohexadienyl complex. Nucleophiles used included LiCMe₂CN (A), LiCH₂CN (B), and (C). The results show that the primary carbanion LiCH₂CN and the S-stabilized carbanion give mixtures of α- and β-substituted products and in both cases α-isomers were major, whereas the opposite regioselectivity was obtained with the tertiary carbanion LiCMe₂CN.     

Electrochemical oxidative selenylation of imidazo[1,2–a]pyridines with diselenides

Electrochemical oxidative selenylation of imidazo[1,2–a]pyridines has been developed. The reaction proceeds in an undivided electrochemical cell equipped with glassy carbon electrodes employing LiClO₄ as a supporting electrolyte. This approach is environmentally benign by using shelf-stable diselenides as selenium source and electrons as oxidizing reagents. The present protocol offers a facile way to prepare 3-selenylated imidazopyridine derivatives.     

Synthesis of new 10,11-dihydrodibenzo[a,d]cycloheptene S-thiocarbamate derivatives via a benzylic Newman–Kwart rearrangement

New S-thiocarbamates possessing a 10,11-dihydro-5H-dibenzo[a,d]cycloheptene moiety were obtained unexpectedly in the process of preparing new O-thiocarbamates starting from 5-dibenzosuberol (10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ol) and aroyl-isothiocyanates. These compounds were obtained via a benzylic Newman–Kwart rearrangement mechanism. The structures of the new thiocarbamates were confirmed by elemental analysis, IR, and NMR spectroscopy and by X-ray crystallography.     

[2+2] Photodimerization of (Z)-4-styrylpyridine through a cation-π interaction: formation of cis-cis-trans dimers

The cis-cis-trans cyclobutanes are prepared by photodimerization of (Z)-4-styrylpyridine. A catalytic amount of HCl plays a key role in enhancing the [2+2] photocyclization reactions between (Z)- and (E)-4-styrylpyridines to give r-cct and r-ctc cyclobutane dimers through a cation-π interaction.     

Cooperative N–H···N,N–H···O,and O–H···N bonded molecular dimers of two new 3,5-diaryl-1<Emphasis Type="Italic">H</Emphasis>-pyrazoles

Two new 3,5-diaryl-1H-pyrazoles: 3(5)-(4-tert-butylphenyl)-5(3)-(naphthalene-2-yl)-1H-pyrazole (1) and 5-(4-(benzyloxy)phenyl)-3-(furan-2-yl)-1H-pyrazole (2) were synthesized and characterized. Two strong ions peaks [2M]⁺ and [2M + Na]⁺ observed in the ESI–MS spectra are attributed to the dimerization process in solution formed by intermolecular N–H···N hydrogen bonds. The crystal structures have been determined by X-ray crystal structure analysis. Compound 1 exists as a pair of tautomers 1a and 1b, and its dimer [R ₂²(6) motif] is formed by the tautomers 1a and 1b. Compound 2 only exists as a 2a tautomer, and interesting intermolecular N–H···O and O–H···N hydrogen bonds link two pyrazoles and two methanol molecules, leading to the formation of an R ₄⁴(10) dimer motif.     

Synthesis of 1,3,5-alternate azacalix[3]pyridine[3]pyrimidine and its complexation with fullerenes via multiple π/π and CH/π interactions

Azacalix[3]pyridine[3]pyrimidine was synthesized efficiently by means of a [3+3] fragment coupling approach. Adopting a preorganized symmetric 1,3,5-alternate conformation, the macrocycle formed complexes with fullerenes through the multiple intramolecular π/π and CH/π interactions.     

Synthesis of 9-nitro-5H-spiro[benzo[b]tetrazolo[1,5-d][1,4]oxazepine-4,2′-oxirane] via an unusual ring-expansion

Attempted cyclization of (4-(hydroxymethyl)-8-nitro-4H-benzo[b]tetrazolo[1,5-d][1,4]oxazin-4-yl)methyl 4-methylbenzenesulfonate 2 did not give the expected spirooxetane product 1, but instead provided 9-nitro-5H-spiro[benzo[b]tetrazolo[1,5-d][1,4]oxazepine-4,2′-oxirane] 3via an unusual ring-expansion process. The structure of compound 3 was confirmed by single-crystal X-ray crystallography. The spiroepoxide (oxirane) in compound 3 could be ring-opened with a variety of nucleophiles to give products of potential interest to medicinal chemists.     

Oxone®-mediated direct arylselenylation of imidazo[2,1-b]thiazoles,imidazo[1,2-a]pyridines and 1H-pyrazoles

Oxone mediated reaction of imidazo[2,1-b]thiazole, imidazo[1,2-a]pyridine and 1H-pyrazole derivatives with diaryl diselenides is presented here. The methodology represents an efficient and simple protocol for carrying out the selective synthesis of 5-arylselanyl-imidazo[2,1-b]thiazoles, 3-arylselanyl-imidazo[1,2-a]pyridines and 4-arylselanyl-1H-pyrazoles in high yields using a stable, nontoxic and cheap oxidant. The reactions were conducted at 60?°C in air using acetonitrile as solvent. Alternatively, the use of ultrasound irradiation is presented as a tool for fast and efficient energy transfer that significantly reduced the reaction time.     

N,N′-methylenedipyridinium Pt(II) and Pt(IV) hybrid salts: synthesis, crystal and molecular structures of [(C5H5N)2CH2] · [PtCl4] and [(C5H5N)2CH2] · [PtCl6]

The highly insoluble organic-inorganic hybrid ionic compounds N,N??-methylenedipyridinium tetrachloroplatinate(II) [(C₅H₅N)₂CH₂] · [PtCl₄] and N,N??-methylenedipyridinium hexachloroplatinate(IV) [(C₅H₅N)₂CH₂] · [PtCl₆] were obtained by the treatment of N,N??-methylenedipyridinium dichloride monohydrate [(C₅H₅N)₂CH₂]Cl₂ · H₂O with K₂[PtCl₄] or (NH₄)₂[PtCl₆], respectively, in an aqueous solution. Both complexes were isolated, purified, characterised by elemental analysis, and their molecular structures were confirmed by powder X-ray diffraction. The crystal structure of both compounds consists of separated discrete dications [(C₅H₅N)₂CH₂]²⁺ and anions [PtCl _n ]^2? (n = 4 or 6). As anticipated, the dications formed a butterfly shape consisting of two pyridine rings bound to the methylene group via their N atoms, while the Pt centre had a square planar geometry in [(C₅H₅N)₂CH₂] · [PtCl₄] and an octahedral coordination in [(C₅H₅N)₂CH₂] · [PtCl₆]. Interestingly, both crystal structures are stabilised by intermolecular C-H??Cl non-standard hydrogen bonds, ??-?? ring interactions between two pyridine rings of adjacent dications, and also by Cl-?? interactions.     

Synthesis of 2-aryl-5-alkyl-7-methoxylbenzo[b]furan derivatives

A series of 2-aryl-5-alkyl-7-methoxylbenzo[b]furan derivatives have been synthesized by utilizing the coupling of methyl 3-methoxy-4-hydroxy-5-bromocinnamate with cuprous phenylacetylide as the key step.The structures of the new compounds were confirmed by1H NMR,IR and MS.The structure of compound 14 was further confirmed by single crystal X-ray.Compound 17 showed cytotoxic activity against human lung carcinoma A549.     

Sc[N(SO2C8F17)2]3 catalyzed condensation of β-naphthol and aldehydes in fluorous solvent: One-pot synthesis of 14-substituted-14H-dibenzo[a,j]xanthenes

A facile synthesis of 14-substituted-14H-dibenzo[a,j]xanthenes was proposed by one-pot condensation of β-naphthol with aryl or alkyl aldehydes by using Scandium bis(perfluorooctanesulfonyl)imide complex as catalyst and perfluorodecalin as sole solvent.     

Synthesis and structure of bismuth-containing complexes [Ph3PMe] 2 + [BiI5]2− and [Ph3PMe] 2 + [BiI5 · C5H5N]2− · C5H5N

The complexes [Ph₃PMe] ₂ ⁺ [BiI₅]^2? (I) and [Ph₃PMe] ₂ ⁺ [BiI₅ · C ₅H₅N]^2? · C ₅H₅N (II) were synthesized by the reaction of bismuth triiodide with triphenylmethylphosphonium iodide, and their structures were determined by X-ray diffraction analysis. The P atom in cation I has slightly distorted tetragonal coordination polyhedron (the CPC angles 109.42(4)° and 109.52(4)°, the bond lengths P-C_Ph 1.779(2), P-C_Me 1.793(1) Å. The Bi atom in the anion of complex I has an ideal trigonal-bipyramidal coordination polyhedron (Bi-I_eq 3.0031(4), Bi-I_eq 3.0485(5) Å). The crystal of complex II consists of the anions [BiI₅ · C ₅H₅N]^2?, solvated pyridine molecules, and two types of crystallographically independent tetrahedral triphenylmethylphosphonium cations (the angles CPC 106.9(1)°–111.7(1)°, the distances P-C_Ph 1.785(3)–1.792(3), P-C_Me 1.793(3), 1.786(3) Å). The Bi atoms in the anion of complex II have a distorted octahedral coordination polyhedron (Bi-I 3.0878(4)–3.1240(3), Bi-N(1) 2.628(3) Å).     

2-Allyl-N-benzyl substituted α-naphthylamines as building blocks in heterocyclic synthesis. New and efficient syntheses of benz[e]naphtho[1,2-b]azepine and naphtho[1,2-b]azepine derivatives

A new series of 13-acetyl-7,12-dihydro-7-ethylbenz[e]naphtho[1,2-b]azepine (4a-d) and 2-aryl-4-hydroxy-2,3,4,5-tetrahydronaphtho[1,2-b]azepine derivatives (6a-d) have been synthesized from N-allyl-N-benzyl substituted α-naphthylamines (1a-d) by utilizing aromatic amino-Claisen rearrangement, intramolecular Friedel-Crafts alkylation and intramolecular dipolar 1,3-cycloaddition nitrone-olefin reactions.     

Yb(OTf)3 catalyzed condensation reaction of β-naphthol and aldehyde in ionic liquids: a green synthesis of aryl-14H-dibenzo[a,j]xanthenes

A facile, efficient and green synthesis of aryl-14H-dibenzo[a,j]xanthenes has been developed by one-pot condensation of β-naphthol and substituted benzaldehydes in the presence of ytterbium triflates in ionic liquids.     

Total synthesis of benzo[c]phenanthridine alkaloids based on a microwave-assisted electrocyclic reaction of the aza 6π-electron system and structural revision of broussonpapyrine

Total syntheses of the des-N-methyl (nor) type of benzo[c]phenanthridine alkaloids 1a-f and 19 and benzo[c]phenanthridine alkaloids, chelerythrine (2d), and broussonpapyrine (2f) were achieved. The key step was the construction of tetracyclic 10,11-dihydrobenzo[c]phenanthridines using a microwave-assisted electrocyclic reaction of the 2-cycloalkenylbenzaldoxime methyl ether 4 as an aza 6π-electron system, which was derived in two steps from a Suzuki-Miyaura cross-coupling reaction of 2-bromobenzaldehyde 6 with 2-(3,4-dihydro-6,7-methylenedioxynaphthyl)boronic acid pinacol ester 7. In addition, the exact structure of broussonpapyrine (2f) (2,3,9,10-tetraoxygenated type) was determined to be chelerythrine (2d).     

Synthesis of novel spiro[benzo[4,5]thiazolo[3,2-a]chromeno[2,3-d]pyrimidine-14,3′-indoline]-1,2′,13(2H)-triones via three component reaction

A new and efficient method for the synthesis of hitherto unreported spiro[benzo[4,5]thiazolo[3,2-a]chromeno[2,3-d]pyrimidine-14,3′-indoline]-1,2′,13(2H)-triones was developed via the Domino Knoevenagel condensation–Michael addition–intermolecular cyclization sequences of isatin derivatives, cyclohexane-1,3-diones, and 2-hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-ones, employing 12-tungstophosphoric acid (H₃PW₁₂O₄₀) as an effective and inexpensive catalyst.     

Substituted benzoquinazolinones. Part 1: Synthesis of 6-aminobenzo[h]quinazolinones via Buchwald–Hartwig amination from 6-bromobenzo[h]quinazolinones

6-(Morpholin-4-yl)benzo[h]quinazolin-4(3H)-one derivatives 18a,b were prepared under Buchwald–Hartwig conditions by reacting 6-bromobenzo[h]quinazolin-4(3H)-ones 13a,b with morpholine in the presence of a Pd(OAc)₂/XantPhos system in 1,4-dioxane as solvent. The starting 6-bromobenzo[h]quinazolin-4(3H)-ones 13 were synthesized via condensation of the ethyl 1-amino-4-bromonaphthalene-2-carboxylate (11) with formamide (Niementowski reaction), and then reaction of the obtained benzoquinazolinone 9 with appropriates benzyl bromides. Compound 11 was prepared using a three-step procedure involving (a) metalation of the N-Boc- or N-Piv-protected 1-aminonaphthalenes with t-BuLi, followed by reaction with ethyl chloroformate, (b) bromination of the naphthalene ring of ester 3 using NBS, and next (c) deprotecion of the amine group with TFA or HCl. Biological screening of the potential cytotoxicity of compounds 8, 9, 18b on A549 and HT29 cell lines, as well as on the lymphocytes showed that compound 18b has interesting anticancer activities. The detailed synthesis, spectroscopic data, and biological assays were reported.     

Central-to-axial chirality transfer and induced circular dichroism in 6,7-dihydro-5H-dibenz[c,e]azepine derivatives of α- and β-amino esters

DAZ-Xaa^∗-OMe amino ester derivatives with Xaa^∗ = d/l-Ala, d/l-Val, l-Leu, l-Ile, l-Ser, l-β³-HAla, l-β³-HVal, l-β³-HLeu, (1S,2S)/(1R,2R)-ACHC (2-aminocyclohexanecarboxylic acid) and (1S,2S)/(1R,2R)-ACPC (2-aminocyclopentanecarboxylic acid), N-blocked as 6,7-dihydro-5H-dibenz[c,e]azepines (DAZ), have been synthesized and evaluated for the determination of the absolute configuration of α- and β-amino esters through the induced circular dichroism of the biphenyl chromophore.     

Synthesis of 2-aryl-2H-[1,2,4]triazoloquinolin-3-one and 2-aryl-2H-[1,2,4]triazoloisoquinolin-3-one derivatives from α-chloroformylarylhydrazines hydrochloride

The reaction of α-chloroformylarylhydrazines hydrochloride with quinoline under air provided the corresponding 2-aryl-2H-[1,2,4]triazoloquinolin-3-ones 3a-3d in 33-42% yields and unexpected isomeric 2-aryl-2H-[1,2,4]triazoloisoquinolin-3-ones 4a-4d in 30-42% yields. These two isomers were isolated and fully characterized by spectroscopic methods including X-ray crystallography. By employing 3-methylquinoline as the starting material under the same condition, the reaction only gave compound 3e-3h as sole products in 70-82% yields without the formation of isomers. A plausible mechanism was proposed through electrophilic aromatic reaction, the tandem ring cyclization and ring-opening, and oxidation for the generation of 2-aryl-2H-[1,2,4]triazoloisoquinolin-3-ones (4).     

Structure-property relationships of benzo[2,1-b:3,4-b’]bis[1]benzothiophenes for organic field effect transistors

A series of novel benzo[2,1-b:3,4-b’]bis[1]-benzothiophene (BBBT) derivatives with different side-chains were synthesized and characterized. And their mobility properties were evaluated based on their active layers in OFETs devices. By means of simple thermal annealing, the devices based on BBBT-4 and BBBT-6 exhibited typical p-type FETs behavior with average hole mobilities of 0.28 and 0.124?cm² V^?1?s^?1, respectively. Furthermore, the structure-property relationships of these semiconductors were also investigated by XRD and AFM.