A ‘One-Pot’ Anellation Method for the Transformation of Heptalene-4,5-dicarboxylates into Benzo[a]heptalenes

It has been found that dimethyl heptalene-4,5-dicarboxylates, when treated with 4 mol-equiv. of lithiated N,N-dialkylamino methyl sulfones or methyl phenyl sulfone, followed by 4 mol-equiv. of BuLi in THF in the temperature range of ?78 to 20°, give rise to the formation of 3-[(N,N-dialkylamino)sulfonyl]- or 3-(phenylsul-fonyl)benzo[a]heptalene-2,4-diols of. (cf. Scheme 4, and Tables 2 and 3). Accompanying products are 2,4-bis{[(N,N-dialkylamino)sulfonyl]methyl}- or 2,4-bis[(phenylsulfonyl)methyl]-4,10a-dihydro-3H-heptaleno[1,10-bc]furan-3-carboxylates as mixtures of diastereoisomers of. cf. Scheme 4, and (Tables 2 and 3) which are the result of a Michael addition reaction of the lithiated methyl sulfones at C(3) of the heptalene-4,5-dicarboxylates, followed by (sulfonyl)methylation of the methoxycarbonyl group at C(5) and cyclization of. (cf. Scheme 5). It is assumed that the benzo[a]heptalene formation is due to (sulfonyl)methylation of both methoxycarbonyl groups of the heptalene-4,5-dicarboxylates of. (cf. Schemes 6 and 8). The resulting bis-enolates 35 are deprotonated further. The thus formed tris-anions 36 can then cyclize to corresponding tris-anions 37 of cyclopenta[d]heptalenes which, after loss of N,N-dialkylamido sulfite or phenyl sulfinate, undergo a ring-enlargement reaction by 1,2-C migration finally leading to the observed benzo[a]heptalenes of. (cf. Schemes 8 and 9). The structures of the new product types have been finally established by X-ray crystal-structure analyses (cf. Figs. 1 and 2 as well as Exper. Part).     

New Azepine-Furan Spirocyclic Structures in the Reaction of 4-Aroyl-1,2-dihydrobenzo[d]azepines and 2-Aroyl-4,5-dihydrophenanthreno[1,2-d]azepine with Formaldehyde

Russian Journal of General Chemistry - 4-Aroyl-1,2-dihydrobenzo[d]azepines, as well as their phenanthro[1,2-d]azepine keto analogs, under the action of formaldehyde in the presence of acid-base...     

Benzo[1,2-b:4,5-b']bis[b]benzothiophene as solution processible organic semiconductor for field-effect transistors

Coplanar benzo[1,2-b:4,5-b']bis[b]benzothiophenes (, ) for the application in organic field-effect transistors were synthesized by a simple two-step procedure involving triflic acid induced ring-closure reaction; such solution processed devices show a hole mobility of up to 0.01 cm(2) V(-1) s(-1).     

1,6:9,14-bismethano[16]annulene - a new bridged [4n]annulene

The molecular structure and dynamic behaviour of the bridged [4n] annulene 1,6:9,14-bismethano-[16]annulene is unravelled by NMR and X-ray investigations, combined with force field calculations.     

First structural authentication of third-sphere coordination: [p-sulfonatocalix[4]arene]5- as a third-sphere ligand for Eu3+

Abstract

The central feature of the complicated structure of Na[Eu₃(p-sulfonatocalix[4]arene)₂(OH₂)18(ONC₅H₅)₃]·14 H₂O is the coordination sphere of one of the three independent europium atoms. Its first coordination sphere consists of seven water molecules, the oxygen atom of a pyridine N-oxide molecule, and a sulfonate oxygen atom from one of the two independent calix[4]arenes. The second-sphere coordination consists of the second calix[4]arene which is bound to the coordinated pyridine N-oxide via hydrophobic interactions, and a second pyridine N-oxide which is hydrogen bonded to a coordinated water molecule. The third-sphere coordination consists of the binding of the second-sphere coordinated pyridine N-oxide to the cavity of the first-sphere coordinated calix[4]arene. Na[Eu₃(p-sulfonatocalix[4]arene)₂(OH₂)₁₈(ONC₅H₅)₃]·14 H₂O crystallizes in the monoclinic space group P2₁/c with a = 20.973(2), b = 18.678(2), c = 29.502(4)Å, β = 109.19(1)°, and D_c = 1.74 g cm^?3 for Z = 4. Refinement based on 10,043 observed reflections led to a final R value of 0.091.     

Reactions of tetrahydropyrido[4,5-d][1,2,4]triazolo[1,5-a]-pyrimidin-4-ones with activated alkynes. Synthesis of [1,2,4]triazolo[1′,5′:1,2]pyrimido[4,5-d]azocines

Triazolo[1′,5′:1,2]pyrimido[4,5-d]azocines were synthesized by the tandem expansion of the tetrahydropyridine ring in tetrahydropyridotriazolopyrimidines by the action of activated alkynes. Under these conditions, triazolopyridopyrimidines benzylated at the nitrogen atom of the pyrimidine moiety undergo the Hofmann cleavage of the tetrahydropyridine ring to form 5-vinyltriazolo[1,5-a]pyrimidines.     

Tetrathiafulvalene (TTF)‐Bridged Resorcin[4]arene Cavitands: Towards New Electrochemical Molecular Switches

We report the synthesis of novel resorcin[4]arene‐based cavitands featuring two extended bridges consisting of quinoxaline‐fused TTF (tetrathiafulvalene) moieties. In the neutral form, these cavitands were expected to adopt the vase form, whereas, upon oxidation, the open kite geometry should be preferred due to Coulombic repulsion between the two TTF radical cations (Scheme 2). The key step in the preparation of these novel molecular switches was the P(OEt)₃‐mediated coupling between a macrocyclic bis(1,3‐dithiol‐2‐thione) and 2 equiv. of a suitable 1,3‐dithiol‐2‐one. Following the successful application of this strategy to the preparation of mono‐TTF‐cavitand 3 (Scheme 3), the synthesis of the bis‐TTF derivatives 2 (Scheme 4) and 19 (Scheme 5) was pursued; however, the target compounds could not be isolated due to their insolubility. Upon decorating both the octol bowl and the TTF cavity rims with long alkyl chains, the soluble bis‐TTF cavitand 23 was finally obtained, besides a minor amount of the novel cage compound 25a featuring a highly distorted TTF bridge (Scheme 6). In contrast to 25a , the deep cavitand 23 undergoes reversible vase → kite switching upon lowering the temperature from 293 to 193 K (Fig. 1). Electrochemical studies by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) provided preliminary evidence for successful vase → kite switching of 23 induced by the oxidation of the TTF cavity walls.     

Structurally-tuned benzo[1,2-b:4,5:b']dithiophene-based polymer as a dopant-free hole transport material for perovskite solar cells

For highly efficient and stable perovskite solar cells (PSCs), hole transport material (HTM) should be designed and synthesized to afford suitable energy levels, high charge transport, efficient passivation ability, and high device stability. Here, we systematically modulated benzo[1,2-b:4,5:b']dithiophene-based polymer by finely controlling the thienyl and pyridyl contents within the conjugated backbone in order to develop a high performance dopant-free HTM for PSCs. We found that the optimized copolymer with 25% of pyridine content exhibits improved energy level, charge transport, and morphology compared with control homopolymers. As a result, remarkably high power conversion efficiencies up to 21.1% were achieved by employing the optimized polymer as a dopant-free HTM in PSCs.     

Ecofriendly synthesis and biological evaluation of 4-(4-nitro-phenyl)-2-phenyl-1,4-dihydro-benzo[4,5]imidazo[1,2-a]pyrimidine-3-carboxylic acid ethyl ester derivatives as an antitubercular agents

An ecofriendly route has been investigated for the synthesis of 4-(4-nitro-phenyl)-2-phenyl-1,4-dihydro-benzo[4,5]imidazo[1,2-a]pyrimidine-3-carboxylic acid ethyl ester derivatives by one-pot, three-component condensation of ethyl benzoylacetate, aromatic aldehydes, and 2-amino benzimidazole using 260?mol% of citric acid as reaction mediator. Citric acid is an inexpensive, nontoxic, and green medium with smoothly activates the rate of reaction. The synthesized compounds were assessed for in vitro antimycobacterial activity against Mycobacterium tuberculosis H₃₇RV strain using the microplate alamar blue assay (MABA). The results indicate that among all the synthesized compound series, P-4 and P-9 compounds illustrate effective activity with a minimum inhibitory concentration of 25?µg/ml.     

Unprecedented Ring Contractions in Cytochalasans: Formation of [10]cytochalasans and a cyclohepta[4,5]benz[1,2-d]isoindole derivative

A series of transformations of cytochalasin D ( 1 ; zygosporin A) was carried out. After treatment of the diol 7 with mesyl chloride and pyridine, and subsequent chromatography on silica gel, the 17-acetyl derivatives 12 and 13 , the first members of the hitherto unknown [10]cytochalasans, were obtained. The alcohol 8 was converted to the chlorosulfinate 18 under the same conditions. Replacement of pyridine by triethylamine in the mesylation reaction led to the cyclohepta[4,5]benz[1,2-d]isoindole derivative 20 , also representing a novel ring system.     

Molecular structure of 10,10-dimethyl-7H-pyrano[4′,3′:4,5]thieno[3,2-e]-(1,2,4)-triazolo[2,3-e]pyrimidine

Institute of Fine Organic Chemistry, Armenian Academy of Sciences. A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 197–199, September–October, 1994.     

Convenient synthesis of 5,6,11,12,17,18- hexahydrocyclononal[1,2-b:4,5-b':7,8-b'']triindole,a novel phytoestrogen

An efficient one-pot synthesis is described of 5,6,11,12,17,18-hexahydrocyclononal[1,2-b:4,5-b':7,8-b']triindole (CTr), a potent estrogen agonist from food plants. For the procedure, gramine is treated with dimethyl sulfate and sodium in ethanol at room temperature. Quenching of the reaction with water and workup of the product provides CTr in approximately 75% yield.     

Synthesis of 2-(1-methyl-4-piperylid-3-ene)-9,10-dihydro-4H-benzo[4,5]- cyclohepta[1,2-b]thiophen-10-one,a new potential antiasthmatic analogue of zaditene

The title compound has been prepared in four steps from readily available starting material. The key reaction is the metallation of 10-methoxy-4H-benzo[4,5]cyclohepta[1,2-b]thiophene, which occurs exclusively at the desired 2 position.