Understanding the orientation and dynamic motion of planar heterocyclic N-donor ligands by exploiting the symmetry properties of mixed-ligand mu-oxorhenium(V) dinuclear complexes

Factors influencing the orientation and dynamic motions of planar N-donor heterocyclic ligands (L) are of interest since such features have broad relevance in metallobiochemistry [Marzilli, L. G.; Marzilli, P. A.; Alessio, E. Pure Appl. Chem. 1998, 70, 961-968]. We found that mu-oxorhenium(V) dinuclear complexes [ReOCl2LsLt]-O-[ReOCl2LsLt] bearing either symmetrical (L = py = pyridine; 3,5-lut = 3,5-lutidine) or lopsided (L = Me3-Bzm = 1,5,6-trimethylbenzimidazole) cis L ligands are particularly useful for studying these factors. NMR data showed that terminal (Lt) and stacked (Ls) ligands were exchanged by approximately 180 degrees rotation about the Re-O-Re bond system. Such exchange occurred, however, between degenerate chiral conformers. Here we report a combined X-ray structural and solution NMR investigation of the AA + CC (racemic) and AC (meso) forms of two mixed-ligand mu-oxorhenium dimers that bear one lopsided and one symmetrical ligand on each Re atom, namely, Re2O3-Cl4(py)2(Me3Bzm)2 (1rac and 1meso) and Re2O3Cl4(3,5-lut)2(Me3Bzm)2 (2rac and 2meso). The presence of two different cis L ligands in 1 and 2 breaks the local symmetry at each Re atom, so that, in the racemic dimers, the exchange of terminal and stacked ligands leads to nondegenerate conformers. Overall, NMR data showed that the unsymmetrical dimers 1 and 2 undergo two dynamic processes contemporaneously, namely, 180 degrees rotation about the Re-N(py or 3,5-lut) bond and coupled rotation about the Re-O-Re/Re-N bonds. Both processes reach the slow exchange limit below -80 degrees C. Rotation of py in 1 occurs faster than that of 3,5-lut in 2; this difference is attributed to the higher steric demands of 3,5-lut compared to py. For both dimers NMR data provided compelling evidence of the preferred conformers in solution, including ligand orientations. The low-T solution structure of 1meso and 2meso is chiral, the same as that found in the solid state for 2meso, where the Me3Bzm on one Re atom is stacked with the 3,5-lut on the other Re atom. The remaining Me3Bzm and 3,5-lut, one on each Re atom, are both terminal. In solution the coupled Re-O-Re/Re-N rotations interconvert the two halves of each meso dimer to yield the same overall stable chiral conformation. For the racemic dimers, however, this process does not interconvert one enantiomer into the other, but instead interconverts two rotamers, R1 and R2, each of which is chiral. We found that, in the case of both 1rac and 2rac, the conformer with stacking symmetrical ligands (R1) is roughly 1 order of magnitude more stable than that with stacking Me3Bzm ligands (R2). Moreover, the solution conformation of R1 is the same as that found in the solid state of 1rac. Solution- and solid-state data indicate that the key interaction favoring the observed conformations is very likely the electrostatic attraction between the delta+ H2 atoms on the Me3Bzm ligands and the negative O and Cl groups in the core of the dimers. Finally, for both meso and racemic dimers we were also able to elucidate the preferred pathways of the coupled dynamic motions and establish that, very likely, the two halves of the dimers swing back and forth by approximately 130 degrees through the anti eclipsed form.     

Sequential approach to the synthesis of 'U and Z' shaped polycyclic heteroarenes

The synthesis of three new classes of heteroarenes, built through the sequential fusion of naphthalene, benzo/naphtho[b]oxepine and thiochromene rings with pyran and pyrimidine ring systems to give 'U and Z' shaped structural frameworks is reported. The methodology is based on the synthesis of pyran fused intermediates, 1-methylthio-3-oxo-5,6-dihydro-3H-benzo[f]chromene-2-carbonitrile (3), 4-methylthio-2-oxo-5,6-dihydro-2H-benzo/naphtho[b]pyrano[2,3-d]oxepine-3-carbonitriles (10, 20) and 4-methylthio-2-oxo-2,5-dihydrothiochromeno[4,3-b]pyran-3-carbonitriles (15) from the reaction of 2-tetralone, benzo/naphtho[b]oxepin-5-ones and thiochromen-4-ones with methyl 2-cyano-3,3-dimethylthioacrylate respectively. Further condensation of intermediates 3, 10, 20 and 15 with amidines led to the formation of tetracyclic 'U' shaped 4-amino-2-aryl-7,8-dihydro-5-oxo-5H-naphtho[2,1-b]pyrimido[4,5-d]pyrans (8) and 'Z' shaped 4-amino-2-aryl-5-oxo-12,13-dihydro-5H-benzo/naphtho[b]oxepino[5,4-b]pyrimido[4,5-d]pyrans (12, 22) and 4-amino-2-aryl-5-oxo-5,12-dihydrothiochromeno[4,3-b]pyrimido[4,5-d]pyrans (17). Compound 12f forms a chain of dimers through N-HO interactions as indicated by the X-ray structure analysis, and the quantum chemical calculations performed at the MP2 level indicate that this interaction energy is 10 kJ mol(-1).     

N(1)-C(5')-linked dimer hydrates of 5-substituted uracils produced by anodic oxidation in aqueous solution

Electrochemical dimerization reactivity has been studied for 5-substituted uracils (5XU) including thymine (1a: X = Me) and 5-halouracil derivatives (1b: X = F; 1c: X = Cl; 1d: X = Br; 1e: X = I). Upon galvanostatic electrolysis of Ar-saturated aqueous solution 1a underwent anodic oxidation to produce N(1)-C(5')- and N(1)-C(6')-linked dimer hydrates, 1-(6'-hydroxy-5',6'-dihydrothymin-5'-yl)thymine (5a) and 1-(5'-hydroxy-5',6'-dihydrothymin-6'-yl)thymine (6a), as the major products. These N-C-linked dimerizations were accompanied by the formation of novel stereoisomeric C(5)-C(5')-linked dimers (meso isomer: 13a[meso]; racemic isomer: 13a[rac]) with a condensed tetrahydrofuran ring skeleton. Similar electrolyses of 5-fluorouracil (1b) and 5-chlorouracil (1c) also afforded the corresponding N(1)-C(5')-linked dimer hydrates, 1-(5'-fluoro-6'-hydroxy-5',6'-dihydrouracil-5'-yl)-5-fluorouracil (5b) and 1-(5'-chloro-6'-hydroxy-5',6'-dihydrouracil-5'-yl)-5-chlorouracil (5c), respectively, while resulting in neither N(1)-C(6')-linked dimer analogues nor C(5)-C(5')-linked dimers, unlike the reactivity of 1a. In contrast to 1a-c, no dimeric products were obtained from 5-bromouracil (1d) and 5-iodouracil (1e). The present electrochemical method was applicable to the cross-dimerization into N(1)-C(5')-linked heterodimer hydrates composed of binary 5-substituted uracils that occurred in competition with the formation of homodimer hydrates. A mechanism of the N(1)-C(5')-linked dimerization of 1a-c has been proposed, by which allyl-type radical intermediates with limiting mesomeric forms of N(1)-centered and C(5)-centered pyrimidine radicals (2a-c [N(1)]/2a-c [C(5)]) are generated via anodic one-electron oxidation and subsequent deprotonation at N(1) and undergo a head-to-tail coupling.     

Synthese und Chiralität von (5S, 6R)-5,6-Epoxy-5,6-dihydro-β,β-carotin und (5R, 6R)-5,6-Dihydro-β,β-carotin-5,6-diol,einem Carotinoid mit ungewöhnlichen Eigenschaften

Synthesis and Chirality of (5S,6R)-5,6-Epoxy-5,6-dihydro-β,β-carotene and (5R,6R)-5,6-Dihydro-β,β-carotene-5,6-diol, a Compound with Unexpected Solubility Characteristics Wittig-condensation of azafrinal ( 1e ) with the phosphorane derived from 7 leads to a (1:3)-mixture of (E)-9′- and (Z)-9′-β,β-carotene-diol 3 , from which pure and optically active 3 ((5R,6R)-5,6-dihydro-β,β-carotene-5,6-diol) has been isolated as bright violet leaflets, m.p. 168°. Due to the trans-configuration of the diol moiety and to severe steric hindrance, hydrogen bonding is reduced to such an extent, that 3 behaves much more as a hydrocarbon than as a diol. There is good evidence that the so-called ‘β-oxycarotin’ obtained by Kuhn & Brockmann [15] by chromic acid oxidation of β, β-carotene is the corresponding racemic cis-diol. 3 has been converted into (5S, 6R)-5,6-epoxy-5.6-dihydro-β,β-carotene ( 4 ), m.p. 156°. This transformation establishes for the first time the chirality of a caroteneepoxide (without other O-functions). Full spectral and chiroptical data including a complete assignement of ¹³C-chemical shifts for azafrin methyl ester and 3 are presented.     

The syntheses of 4b,5a-dihydro-5H-benzo[3,4]-phenanthro[1,2-b]azirine and 1a,11b-dihydro-6,11-dimethyl-1H-benz[3,4]anthra[1,2-b]azirine

The syntheses of the K-imine derivatives of carcinogenic benzo[c]phenanthrene and 7,12-dimethylbenz-[a]anthracene are described. Treatment of trans-5-azido-5,6-dihydrobenzo[c]phenanthren-6-ol ( 3 ) and trans-6-azido-5,6-dihydrobenzo[c]phenanthren-5-ol ( 5 ) with thionyl chloride yielded the corresponding β-chloro azides, which in turn, were reacted with lithium aluminium hydride to give 4b,5a-dihydro-5H-benzo[3,4]-phenanthro[1,2-b]azirine ( 2 ). In a similar manner trans-5-azido-5,6-dihydro-7,12-dimethylbenz[a]anthracen-6-ol ( 11 ) and trans-6-azido-5,6-dihydro-7,12-dimethylbenz[a]anthracen-5-ol ( 13 ) were transformed to the respective chloro azides and, converted into 1a,11b-dihydro-6,11-dimethyl-1H-benz[3,4]anthra[1,2-b]azirine ( 10 ).     

Synthesis,chiroptical properties and absolute configuration of spiro[1,3-benzodioxole-methanocyclooct[b]indole

The synthesis of chiral 1'H-spiro[1,3-benzodioxole-2,12'-[6',10']methanocyclooct[b]indole] 3, a fused polycyclic structure derived from bicyclo[3.3.1]nonane, was accomplished via the Fisher indolization reaction. Enantiomers of this structure were obtained by chiral HPLC enantiomer separation on a swollen microcrystalline triacetylcellulose column. Chiroptical properties of the resolved enantiomers containing indole and 1,2-methylenedioxybenzene chromophores were studied. Application of the sector rule to the 1,2-methylenedioxybenzene chromophore to establish the absolute configuration of this polycyclic structure did not lead to an unequivocal conclusion which is likely to be due to the transannular interaction of the chromophores. The enantiospecific synthesis from enantiomerically enriched (-)-(1R,5S)-bicyclo[3.3.1]nonane-2,9-dione 1 was performed to prove unequivocally the (+)-(6'R,10'S)-configuration of the title structure. This study demonstrates that semiempirical rules should be applied cautiously to the determination of the absolute configuration of molecules containing several chromophores.     

Unexpected Direction of Iodocyclization of 3-Allylthio-5-phenyl-4H-1,2,4-triazole

The reaction of 3-allylthio-5-phenyl-4H-1,2,4-triazole with iodine to give a mixture of 5,6-dihydro-5-iodomethyl-3-phenyl[1,3]thiazolo[2,3-c][1,2,4]triazole, 6,7-dihydro-6-iodo-3-phenyl-5H-[1,2,4]triazolo[3,4-b][1,3]thiazine, 5,6-dihydro-6-iodomethyl-2-phenyl[1,3]thiazolo[3,2-b][1,2,4]triazole, and 6,7-dihydro-6-iodo-2-phenyl-5H-[1,2,4]triazolo[5,1-b][1,3]thiazine has been studied. The structure of the products obtained was established using ¹H NMR spectroscopy of their dehydriodination products.     

Aminolysis of 2-Aryl-5-R-5,6-dihydro-7H-[1,2,4]triazolo[5,1-<Emphasis Type="Italic">b</Emphasis>]1,3]thiazin-7-ones

We have established that the products of aminolysis of 2-aryl-5-R-5,6-dihydro-7H-[1,2,4]triazolo-[5,1-b][1,3]thiazin-7-ones in boiling ethanol are 3-R-3-(5-aryl-4H-1,2,4-triazol-3-ylsulfanyl)-propanamides, and at 180°C–210°C (depending on the structure of the substituent R): 3-phenyl-4,5-dihydro-1H-1,2,4-triazoline-5-thione and 3-arylacrylamides or 3-(3-aryl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl)propanamides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1587–1592, October, 2005.     

New derivatives of 4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrazole, 4,5-dihydro-1,2-oxazole,and pyrimidine prepared proceeding from (<Emphasis Type="Italic">E</Emphasis>)-3-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-one

Condensation of acetylferrocene with 5-phenyl(4-methylphenyl)-1,2-oxazole-3-carbaldehydes afforded (Е)-3-[5-phenyl(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-ones. Reactions of (Е)-3-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-one with semicarbazide, thiosemicarbazide, and hydroxylamine led to the formation of 5-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-3-ferrocenyl-4,5-dihydro-1H-pyrazole- 1-carboxamide, 5-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-3-ferrocenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide, and 5-(4-methylphenyl)-3'-ferrocenyl-4',5'-dihydro-3,5'-bi-1,2-oxazole respectively. Reactions of (Е)-3-[5-(4-methylphenyl)-1,2-oxazol-3-yl]-1-ferrocenylprop-2-en-1-one with guanidine and thiourea result in 4-[5-(4-methyl-phenyl)-1,2-oxazol-3-yl]-6-ferrocenylpyrimidin-2-amine and -2-thione respectively.     

Gallium(iii)-mediated dimerization routes for (5-phenyl-2-thienyl)cyclopropane-1,1-dicarboxylate

A selectivity-switched dimerization process for (5-phenyl-2-thienyl)cyclopropane-1,1-dicarboxylate under activation conditions with anhydrous Gaiii salts was developed. Using GaCl3 or Ga(NTf2)3 as catalysts, 3a,4,5a,6,7,8-hexahydro-5H-pentaleno[6a,1-b]thiophene and 5,6-dihydro-4H-cyclo-penta[b]thiophene derivatives can be selectively obtained as a result of ipso-type and [3+2]-annulation type dimerization. The crucial role of a phenyl substituent at position 5 of the thiophene ring and some regularities are discussed.     

HETEROCYCLIC SYSTEMS CONTAINING BRIDGE HEAD NITROGEN ATOM: REACTION OF 5-MERCAPTO-4H-IMIDAZO[4,5-e]- [2,1,3]BENZOTHIADIAZOLES AND 5,6-DIAMINO[2,1,3]BENZOTHIAZOLE WITH 3-(2-BROMOACETYL)COUMARINS

Condensation of 5-mercapto-4H-imidazo[4,5-e][2,1,3]benzothiadiazole (I) with various 3-(2-bromoacetyl)coumarins, followed by PPA cyclization of the intermediate ketones II, yielded 3-(2,8-dithia 1,3,5b, 9-tetraaza cyclopenta(b)-as-indacen-6-yl)chromen-2-ones III. Reaction of 5,6-diamino[2,1,3]benzothiadiazole with 3-(2-bromoacetyl)- coumarin in anhydrous ethanol containing fused sodium acetate gave the corresponding 2-coumarinyl 3,4-dihydro-1,4-pyrazino[5,6-e][2,1,3]benzothiadiazoles IV.     

Syntheses of 2,3‐dicyano‐5a,8a‐dihydro‐5a‐hydroxycyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines and 2,3‐dicyanocyclohexano[1′,2′:4,5]pyrrolo‐[2,3‐b]pyrazines

Previously synthesized 2‐(3′‐chloro‐5′,6′‐dicyanopyrazin‐2′‐yl)cyclopentan‐1‐one 1 , obtained from the reaction of 2,3‐dichloro‐5,6‐dicyanopyrazine with 1‐pyrrolidino‐1‐cyclopentene, was further reacted with primary alkylamines to give mixtures of diastereomer of 5‐alkyl‐2,3‐dicyano‐5a,8a‐dihy‐dro‐5a‐hydroxycyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines 3a‐h in high yield. The reaction of 2‐alkylamino‐3‐chloro‐5,6‐dicyanopyrazine with 1‐pyrrolidino‐1‐cyclohexene gave 5‐alkyl‐2,3‐dicyanocyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines 5a‐b together with 5‐alkylamino‐2,3‐dicyano‐6‐pyrrolidinopyrazines 6a‐b . The products prepared are all of interest as potential pesticides and new fluorescent chromophores.     

Synthesis of Optically Pure Helicene Metallocenes

Two types of ruthenocenes and a ferrocene coordinated by rac ‐9H ‐cyclopenta[1,2‐c :4,3‐c ′]diphenanthrenyl anion(s), a [7]helicene with a cyclopentadienyl moiety at the center of its skeleton, were successfully synthesized: mono‐helicene ruthenocene 1 and its iron analogue 1_Fe with one [7]helicene ligand bound to the central metal, and bis‐helicene ruthenocene 2 with two [7]helicenes. Starting from a racemic mixture of the ligand precursor, rac ‐ 2 and meso ‐ 2 were obtained in a 7:3 ratio. Since the [7]helicene has a high racemization barrier, enantiomers of the complexes were isolated in their pure forms; they showed large optical rotations and intense circular dichroism (CD) responses.     

Reaction of 2-Aryl-5-R-5,6-dihydro-7H-[1,2,4]-triazolo[5,1-<Emphasis Type="Italic">b</Emphasis>][1,3]thiazin-7-ones with Aryl Bromomethyl Ketones and Benzyl Bromide

The products of the reaction of 2-aryl-5-R-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones with aryl bromomethyl ketones are 2-aryl-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones and aryl methyl ketones or 2,5-diaryl[1,3]thiazolo[3,2-b][1,2,4]triazoles and 3-phenyl-2-propenoic acid, depending on the structure of R. The reaction of 2-aryl-5-R-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones with benzyl bromide yields 5-aryl-3-benzylthio-4H-1,2,4-triazoles and 3-aryl-2-propenoyl bromide. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 905–909, June, 2005.     

Synthesis and characterization of racemic mixture and meso isomers of bis(trans-2-aminocyclohexyl)aminepentaacetic acid and the stabilities of their Gd(III) complexes

The synthesis and characterization of two multidentate ligands, the racemic mixture and meso isomers of bis-(trans-2-aminocyclohexyl)aminepentaacetic acid, are described. Equilibrium constants for their Gd(III) complexes were determined by direct potentiometry. The formation constants (KML = [ML]/[M][L]) of Gd(III)-Cycyracemic in 0.10 M KCl at 25.0 degrees C is 10(20.71; that for the meso isomer is 10(20.42). The crystal structure of (1S,2S,1'S,2'S)-bis(trans-2-aminocyclohexyl)amine-N,N,N',N",N"-pentaacetic acid, penta-tert-butyl ester (C42H75N3O10), is reported. This compound crystallizes in the triclinic system with space group P1 with cell parameters a = 10.805(2) A, b = 11.382(2) A, c = 20.999(4) A, alpha = 91.41(3) degrees, beta = 98.23(3) degrees, gamma = 113.88(3) degrees, V = 2327.8(8) A3, Z = 2, Dx = 1.116 g mL-1. The results are compared to the crystal structures of the gadolinium complexes and the predictions derived from molecular mechanics.     

2-R-5-Ar(Het)-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones

A novel method for synthesis of 2-R-5-Ar(Het)-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones by condensation of 3-R-4,5-dihydro-1H-1,2,4-triazole-5-thiones with 3-aryl(heteryl)-2-propenoyl chlorides is proposed.     

Scope and limitations of the double [4+3]-cycloadditions of 2-oxyallyl cations to 2,2'-methylenedifuran and derivatives

The reactivity of various 2-oxyallyl cations toward 2,2'-methylenedifuran (1b), 2,2'-(hydroxymethyl)difuran (1c), 2,2'-(trimethylsilylmethylene)difuran (1d), and di(2-furyl)methanone (1e) has been explored. Difuryl derivatives 1c, 1d, and 1e refused to undergo formal double [4+3]-cycloadditions. Conditions have been found to convert 1b into meso-1,1'-methylenedi[(1R,1'S,5S,5'R)- (3) and (+/-)-1,1'-methylenedi[(1RS,1'SR,5SR,5'RS)-8-oxabicyclo[3.2.1]oct-6-en-3-one] (4) that do not require CF(3)CH(OH)CF(3) as solvent. High yields of meso-1,1'-methylenedi[(1R,1'S,2S,2'R,4R,4'S,5S,5'R)- (5) and (+/-)-1,1'-methylenedi[(1RS,1'RS,2SR,2'SR,4RS,4'RS,5SR,5'SR)-2,4-dimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one] (6) have been obtained when 1b was reacted with 2,4-dibromopentan-3-one (7h) and NaI/Cu.     

2-Chlorobicyclo[2.2.1]hept-5-ene-2-carboxamide and 2-chlorobicyclo[2.2.1]heptane-2-carboxamide as precursors of bicyclo[2.2.1]hept-5-en-2-one and bicyclo[2.2.1]heptan-2-one: resolution,absolute configuration and hydrogen-bonding properties

The absolute configuration of bicyclo[2.2.1]heptan-2-one has not been correlated with a crystal structure of a chemical precursor. The only chemical correlation available had an ambiguity, which could have reversed the assignment. Herein, we report the resolution of 2-chlorobicyclo[2.2.1]hept-5-en-2-exo-carboxamide on a cellulose triacetate column and the crystal structures of the enantiomerically pure and racemic α-chloroamide. We found the absolute configuration (1R,2R,4R) for the (+)-enantiomer of the α-chloroamide. This compound was converted to (+)-bicyclo[2.2.1]hept-5-ene-2-one by base hydrolysis, and the 5,6-unsaturated compounds converted to the saturated congeners. This is the first unambiguous experimental determination of the absolute configuration of bicyclo[2.2.1]heptan-2-one and of bicyclo[2.2.1]hept-5-ene-2-one. The three crystal structures of 2-chlorobicyclo[2.2.1]hept-5-en-2-exo-carboxamide reported herein reveal H-bonded dimers, with two distinct orientations of the bicyclic portion relative to the carboxamide dimer. In the racemic crystal, each dimer is composed of two enantiomers, and the bicyclic portions have their bridge carbon atom (C-7) on opposite sides of the H-bonded carboxamide dimer moiety. In the enantiomerically pure crystals, the major dimer had both C-7 atoms on the same side of the carboxamide dimer moiety while the minor dimer had the C-7 atoms on opposite sides. The dimers are present in solution, and can be easily monitored.     

Manganese(III) acetate-mediated radical reaction of [60]fullerene with phosphonate esters affording unprecedented separable singly-bonded [60]fullerene dimers

Radical reaction of [60]fullerene with phosphonate esters mediated by manganese(III) acetate in chlorobenzene afforded singly-bonded fullerene dimers, of which the individual meso and racemic isomers could be unexpectedly separated out for the first time.     

Beiträge zur Chemie des 4,5-Dihydro-10H-benzo [5, 6]cyclohepta[1,2-b]thiophens

Several syntheses of 4,5-dihydro-10 H-benzo[5,6]-cyclohepta[1, 2-b]thiophen-10-one (I b) are described. The pharmacological properties of the compounds XIII, which derive from IB through basic substitution on position 10, are briefly mentioned.