Stereochemie von Metallocenen, 43. Mitt.: Torsionsisomere Biphenyl-tricarbonylchrom-Komplexe: Darstellung,Konformationsanalyse und Kinetik der Interkonversion

Complexation of methyl 3-nitro-2-(o-tolyl)-benzoate (2, ano-trisubstituted biphenyl) with hexacarbonyl chromium gave the isomeric Cr(CO)₃ complexes3 and4 both existing as two torsional isomersa andb, as seen by nmr. For the main product3 the preferred conformations of the two torsional isomersa andb were deduced by the lanthanide induced shift (LIS) technique. The activation energy for the interconversion process could be determined from kinetic measurements and especially from¹H-nmr coalescence temperature of the methylsignals. The barrier of 91±1.5 kJ/mol (21.7±0.3 kcal/mol) in3 reflects the interaction of theo-H-atom of the benzene ring passing the Cr(CO)₃ moiety of the benchrotrene ring during the interconversion.A partial optical resolution of3 was achieved by asymmetric reduction with a chiral lithium-aluminium hydride yielding (+)-3 with [] _D ²⁰ +30° (benzene) and the levorotatory alcohol (–)-7.

42. Mitt.:K. Schlögl undR. Schölm, Mh. Chem.109, 1227 (1978).     

Model calculations on LIS,III. A simple force field model for Ln(III)-shift-reagent—Substrate complexes, 1. Carbinols

A force field type of calculation (FFLIS model, force field aided LIS calculation) is presented allowing to predict the lanthanide(III) positionand the relative LIS values for carbinol—Ln(III) complexes.II.:O. Hofer, Mh. Chem.110, 745 (1979).     

Beiträge zur Chemie der Pyrrolpigmente, 41. Mitt.: Kraftfeldrechnungen an Gallenfarbstoffen: Die Energiehyperfläche verdinoider Pigmente

Using a force field previously described, the energy hypersurface around the global energy minimum of the (Z,Z,Z)-Octamethylbilatriene-abc1 was investigated with respect to the torsion angles at positions 5, 9 and 14 yielding informations on the geometry of the global minimum and the transition paths between enantiomeric conformers. The geometry of the most stable conformations were calculated for the diastereomers of1 as well as for the peripherally unsubstituted3 and the N-methylated derivatives4, 5 and6. The conformational behaviour and the relative stabilities of the diastereomers turned out to be dominated by the influence of the peripheral substitution (alkylgroup backbone). The results are in good agreement with earlier experimental results.

40. Mitt.:Falk, H., Schlederer, T., Mh. Chem.112, 501 (1981).     

Reaktivität der Pyrrolpigmente, 2. Mitt.: Deprotonierung von 3-Pyrrolin-2-onen

Deprotonation of 3,4-dimethyl-3-pyrrolin-2-on (1) int-butyl alcohol/potassiumt-butoxide solutions takes place on the N atom, as shown by¹H/²H exchange andpK _a determinations of1 (pK=17.1), 1,3,4-trimethyl-3-pyrrolin-2-one (pK _a =17.6), and 3,4-dimethyl-5-methoxy-2_H-pyrrole (pK _a =16.7). The SCF-MO approximation MINDO/3 indicates, however, that in the gas phase deprotonation of1 should occur at the C atom.

1.Mitt.:Ribó, J. M., Trull, F., Mh. Chem.110, 201 (1979).     

Prins-Reaktionen mit Arylaldehyden, 5. Mitt.: Zur Umsetzung mit 2-Buten und mit Cyclohexen

By reaction of 2-[(1RS, 2RS)-2-hydroxy-1-methyl-propyl]-2-phenyl-1,3-dithiane (1 a) withcis-2-butene oxide, subsequent reduction and acetalizationc-4,t-5-dimethyl-r-2,c-6-diphenyl-1,3-dioxane (3 a) andt-4,c-5-dimethyl-r-2,c-6-diphenyl-1,3-dioxane (3 b) were synthesized as model compounds. For the same purpose by aldol reaction of cyclohexanone and reduction (1RS, 2SR)-2[(RS)-hydroxy-(4-methoxyphenyl)methyl]cyclohexanol (7 a), (1RS, 2RS)-2[(SR)-hydroxy-(4-methoxyphenyl)methyl]cyclohexanol (8 a), and (1RS, 2RS)-2[(RS)-hydroxy-(4-nitrophenyl)methyl]cyclohexanol (8 b) and by acetalization (2 , 4 , 4 a, 8 a)-2,4-bis(4-methoxyphenyl)hexahydro-4H-1,3-benzodioxin (9 a) and (2 , 4 , 4 a, 8 a)-2,4-bis(4-nitrophenyl)hexahydro-4H-1,3-benzodioxin (10 b) were obtained. FromPrins reactions, starting with 2-butene3 a,c-4,c-5-dimethyl-r-2,c-6-diphenyl-1,3-dioxane (3 c),r-4,t-5-dimethyl-c-6-phenyl-1,3,2-dioxathiane-2,2-dioxide (4), and (2Z, 4E)-1,5-diphenyl-4-methyl-2,4-pentadien-1-on (5), and starting with cyclohexene (E)-3-(4-methoxybenzylidene)cyclohexenyl-4-methoxyphenyl ketone (11) have been isolated in low yields.

4. Mitt.:Griengl, H., Nowak, P., Mh. Chem.109, 11 (1978).     

Zur Synthese und Struktur derp-Indazolchinone und ihrer Methylierungsprodukte Untersuchungen über Chinone, 8. Mitt.

Summary Thep-benzoquinones5e-j react with diazomethane (after dehydrogenation) to 6-anilino-2e, dimethylamino-2h, phenylthio-2i, and methylthioindazolquinone2j. Methylation with dimethylsulfate of these as well as of the already known indazolquinones 6-toluidino-2f, 6-methylanilino-2g, 5-tert.butyl-2m, 5,6-methyl- (isomer mixture)2l,n, and benz-indazolquinone2o yield the 1-and 2-N-methyl derivatives3 and4. The structure of the 2-methyl derivatives is established by reaction of the corresponding benzoquinones with 3-methylsydnon in the case of4e,4g. UV/VIS-, IR- and¹H-NMR-spectroscopy (in CDCl₃ andDMSO) were used for structure determination. Comparison of the UV/VIS-spectra of2–4 shows that the indazolquinones are existing as 2 H-4,7-diones. For the structure elucidation of the 1- rs. 2-methylderivatives (whichh can be attributed to the methylation products) NMR-spectroscopy is well suited even without knowing the second isomer (solvent-effect). The course of the reaction of quinones with diazomethane and of the methylation reactions of the indazolquinones is discussed.

Herrn Univ.-Prof. Dr. G. Zigeuner zum 70. Geburtstag gewidmet     

Synthesen und Reaktionen von Pyridazinderivaten, 11. Mitt.: 5-Acyl-4-pyridazincarbonsäurrester als „key intermediates” für 4-Acylpyridazine und 4-Alkyl-bzw. 4-Arylpyridazino[4,5-d]pyridazin-1 (2H) one

A convenient general method of preparing 4-acylpyridazines (4) is reported. It involves homolytic acylation of ethyl-4-pyridazinecarboxylate yielding ethyl-5-acyl-4-pyridazinecarboxylates (2) which easily can be converted to4 by alkaline hydrolysis followed by decarboxylation. The hitherto unknown pyridazino[4,5-d]pyridazine-1 (2H) ones bearing an alkyl- or arylsubstituent on C-4 (5a-g) were prepared in quantitative yields by reaction of2 with hydrazine.

10. Mitt.:G. Heinisch, A. Jentzsch undI. Kirchner, Tetrahedron Lett.1978, 619.     

Zur Kenntnis organischerLewis-Säuren, 36.Cis—trans-Gleichgewichte und Konformationen von 2,(x)-Dialkyl-1-dicyanomethylencyclohexanen. Wahlweise einfache Darstellung dercis- odertrans-Formen

Knoevenagel condensation of malononitrile withcis- andtrans-2,5-dimethylcyclohexanone (1 c and1 t, respectively) leads to2 c and2 t, respectively, and withtrans-1-decalone to4 t. The equilibria2 c2 t and4 c4 t have been determined as well as, by means of 270-MHz-¹H-NMR, the conformations of these four compounds. The dicyanomethylene group is found to induce axial positions of neighbouring alkyl residues on the cyclohexane ring (or when this is impossible, as in the case of4 t, the twist form of the cyclohexane ring). This results in a strong predominance of thecis isomers in the equilibria2 c2 t and4 c4 t whereas thetrans isomers strongly predominate in the equilibria among the starting ketones. This situation allows the optional preparation of2 c or2 t, and of4 c or4 t, from the more stable starting ketone (or ketone mixture). The free conformational energy of the distorted twist form of4 t amounts to 17 kJ/mol.

Herrn Prof. Dr.E. Ziegler, Graz, zum 70. Geburtstag in aufrichtiger Verbundenheit gewidmet.     

Über die Zusammensetzung des Pyrolysates von Weihrauch “Aden”, dem Gummiharz vonBoswellia carteri Birdw., 2. Mitt.

5-Hydroxy-p-menth-6-en-2-one (1) and 10-hydroxy-4-cadinen-3-one (2) were isolated from pyrolytic products of Incense Aden (gum resin ofBoswellia carteri Birdw.). The relative and absolute configurations of these compounds were determined on the basis of spectral and chemical evidences.

Für Darstellung und Auftrennung des Weihrauchpyrolysates einschließlich der SC-Vortrennung siehe     

Über die Zusammensetzung des Pyrolysates von Weihrauch “Aden”, dem Gummiharz vonBoswellia carteri Birdw., 3. Mitt.

1,2,4-Trihydroxy-p-menthane (1) was isolated from the pyrolytic products of incense Aden (gum resin ofBoswellia carteri Birdw.) The relative and absolute configuration of1 was established on the basis of spectral and chemical evidences and also confirmed independently by partial synthesis.

2. Mitt.:Pailer, M. Scheidl, O., Gutwillinger, H., Klein, E., Obermann, H., Mh. Chem.112, 595 (1981).     

Chinazolinone, 2. Mitt.: Synthese und einige Reaktionen von 2-Azidomethyl-3-aryl-4-chinazolinonen

Starting with the chloromethyl compounds7 the new 2-azidomethyl-3-aryl-4-quinazolinones8 a-h were prepared, some of which have been reduced so far to the corresponding amines9 a, b, e, g by H₂S in good yield. As a first example for the capability of the azides8 to undergo 1,3-dipolar cycloaddition the 2-quinazolinmethyl-1,2,3-triazol-4,5-dicarboxylicacid dimethylesters11 b, e, g were prepared by reacting8 with dimethylacetylenedicarboxylate (10).

1. Mitt.:Domanig R., Arch. Pharm., im Druck.     

Michael reaction. IV. NaNH2 catalyzed one stage reaction between phenylacetic acid dialkylamides and cinnamic acid methyl ester or dialkylamides. Influence of reaction conditions on the stereochemistry

The NaNH₂ catalyzed one stage reaction between phenylacetic acid dialkylamides and cinnamic acid methyl ester or dialkylamides was studied under various conditions. Conditions were found for easy preparation of each of the both possible diastereomeric derivatives of 2,3-diphenylglutaric acid. It was proved that catalytic amounts of NaNH₂ take part in the reaction. It is assumed that the observederythro/threo equilibrium ratios are determined by an isomerization via two different carbanions (at C₂ and C₄) of the reaction products.Part III:J. Stefanovsky andL. Viteva, Comun. Dept. Chem. Bulg. Acad. Sci.4, 159 (1971).     

Zur Kenntnis der Reaktionsfähigkeit des Thiomorpholins und alkylsubstituierter Thiomorpholine, 4. Mitt.

Thiomorpholine as well as alkyl substituted thiomorpholines and their Sdioxides, respectively, are transformed into the corresponding N-Aminothiomorpholines by nitrosation (1–5) followed by the reduction with zinc in acetic acid/acetic acid anhydride under simultaneous formation of the corresponding N-acetyl derivates, and hydrolysis by hydrochloric acid (6–9). Examples of this method are described. 4-Aminothiomorpholines and their Sdioxides react with aldehydes or ketones to give azomethines (10–31). Acylation with mono-and dicarbonic acid chlorides leads to the N-acyl derivatives32–44.Mannich condensation is also possible. By oxidation with yellow mercury oxide tetracenes are formed (46–47).

Teil der DissertationM. Schmitz, Techn. Hochschule Aachen, 1975.     

Structures and energies of seleno derivatives of biuret.Ab Initio comparative studies of diselenobiuret, selenobiuret, and selenothiobiuret

Ab initio studies (LCAO-MO method) on conformers of three seleno derivatives of the biuret molecules diselenobiuret [I], selenobiuret [II], and selenothiobiuret [III] were carried out at the Hartree-Fock (HF) and MP2 levels. The molecular geometries of these species were fully optimized at the HF level and characterized by analysis of the harmonic vibrational frequencies using a split-valence triple-zeta basis set augmented by a set ofd polarization functions on heavy atoms andp polarization functions on hydrogen atoms [TZP(d, p)]. The total energies of the HF-optimized structures were calculated at the MP2 (frozen core) level using a larger TZP (2df, 2pd) basis set. The potential energy searches revealed a total of 11 minimum-energy conformers (assigned astrans-trans, trans-cis, cis-trans, andcis-cis) and seven transition-state species for the title molecules. The two predicted conformers for diselenobiuret (Ia=trans-trans andIc=cis-cis) are characterized byC ₂ and the third byC _s symmetry. For selenothiobiuret two forms (IIIa=trans-trans andIIId=cis-cis) possessC ₁ and two (IIIb=trans-cis andIIIc=cis-trans) possessC _s symmetries, respectively. For selenobiuret, four formsIIa=trans-trans (C₁),IIb=trans-cis (C _s),IIc=cis-trans (C ₁), andIId=cis-cis (C₁), were obtained as a result of gradient optimization. Comparison of the relative energies for the considered species indicated that thecis-trans forms are the most stable conformations for all three systems at both the HF and MP2 levels of theory.     

Reaktion von 2-(N-Alkyl-p-hydroxyanilino)-1,4-benzochinonen Diazomethan. N-(Alkyl-p-hydroxyanilino)-4,7-indazolchinone und ihre isomeren N-Methylderivate

The reaction of N-alkyl-p-hydroxyanilinobenzoquinones1 a–d, its acetylderivatives1 ₁–c₁ and the methoxyderivative1 a₂ with diazomethan yields in dependence on the reaction-conditions the indazolquinones2 a–d, 2 a₁–c₁ or2a ₂, the1-methylindazolquinones3 a–d and3 ₁–c₁, and finally the methoxy-1-methylindazolquinones5 a–d. The 2-methyl-isomeres6 a–d are formed only in small amounts. Methylation of2 a with dimethylsulfate gives5 a and6 a in the ratio of appr 2 to 1. Acetylation of2 a–d with acetanhydride leads to the N–O-acetylderivatives, which are easily hydrolyzed to2 a₁–d₁ during work up;3 a d yields3 a₁–d₁. The structures are established by the described crossexperiments and by spectroscopy (UV/VIS, IR, NMR).

Herrn Prof. Dr.G. Zigeuner zum 60. Geburtstag gewidmet.     

2-[3-(Trifluoromethyl)phenyl]furo[3,2-b]pyrroles: synthesis and reactions

The synthesis and reactions of methyl 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole-5-carboxylate (1a) are described. Upon reaction with methyl iodide, benzyl chloride, or acetic anhydride, this compound gave N-substituted products 1b-d. By hydrolysis of compounds 1a-c, the corresponding acids 2a-c were formed, or by reaction with hydrazine-hydrate, the corresponding carbohydrazides 3a-c were formed. By heating 2-[3-(trifluoromethyl)phenly]-4H-furo[3,2-b]pyrrole-5-carboxylic acid (2a) in acetic anhydride, 4-acetyl-2-[3-(trifluoromethyl)phenyl]furo[3,2-b]pyrrole (4) was formed. By hydrolysis of 4, 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole (5a) was formed, and reactions with methyl iodide or benzyl chloride gave N-substituted products 5b-c. The reaction of 4 with dimethyl butynedioate gave substituted benzo[b]furan 6. Compound 3a reacted with triethyl orthoesters giving 7a-c, which afforded with phosphorus (V) sulphide the corresponding thiones 8a-c. The thiones 8a-c reacted with hydrazine hydrate to form hydrazine derivatives 9a-c. The reaction of triethyl orthoformiate with compounds 9a-c led to furo[2′,3′: 4,5]pyrrolo[1,2-d][1,2,4]triazolo[3,4-f][1,2,4]triazines 10a-c. Hydrazones 11a-c were formed from 3a-c and 5-[3-(trifluoromethyl)phenyl]furan-2-carboxaldehyde. The effect of microwave irradiation on some condensation reactions was compared with “classical” conditions. The results showed that microwave irradiation shortens the reaction time while affording comparable yields.     

New thallium(III) chloride complexes with pyridine carboxylic acids: from molecular compounds to supramolecular associations

Reactions of TlCl₃ with picolinic acid (Hpic), nicotinic acid (Hnic), isonicotinic acid (Hinic) and 3-hydroxy-picolinic acid (H3hpic) afford the isolation of new chlorothallium(III) complexes. The compounds are characterized by IR, Raman and multinuclear NMR (¹H,¹³C,²⁰⁵Tl). The molecular structures of [TlCl₂(pic)(Hpic)]·0.5H₂O (1), [TlCl₂(nic)(Hnic)] (2), [TlCl(inic)₂]·0.6C₂H₅OH (3) and [TlCl(3hpic)₂(h3hpic)] (4) are determined by single-crystal X-ray diffraction. A distorted octahedral TlCl₂N₂O₂ core containing the O,N-chelating ligands is achieved in the monomeric complex 1. The coordination polyhedron in compounds 2–4 is pentagonal bipyramidal, i.e. TlCl₂NO₄ in 2, and TlClN₂O₄ in 3 and 4, respectively. O,O′,N-Bridging ligands result in a polymer chain for 2 and a three-dimensional polymeric association in 3, while compound 4 is monomeric (O, N-and O,O-chelating ligands).     

New chiral spiro[2.5]octanones as products of methylenation of (3<Emphasis Type="Italic">R</Emphasis>, 6<Emphasis Type="Italic">R</Emphasis>)-2-arylidene-6-isopropyl-3-methylcyclohexanones with dimethylsulfoxonium methylide. Synthesis,stereochemistry, and behavior in liquid-crystalline systems

Methylenation of (3R,6R)-2-(4-X-benzylidene)-6-isopropyl-3-methylcyclohexanones (X = F, Cl, Ph) with dimethylsulfoxonium methylide occurs stereoselectively to give 1(S)-(4-X-phenyl)-5(R)-isopropyl-8(R)-methyl-3(R)-spiro[2.5]octanones, whose stereochemistry was established by ¹H NMR spectroscopy. The configuration of the chiral centers in the cyclohexanone fragment and its preferred conformation (methyl is axial and isopropyl is equatorial) in the products do not change with respect to the starting enones. The mutual trans-arrangement of the carbonyl and aryl groups at the newly formed three-membered ring was established; the aryl group also occupies the trans-position with respect to the axial methyl group of the cyclohexanone fragment. Using methylenation of the compound with X = Ph as an example, a mixture of by-products resulting from oxidative hydroxylation at the α-position relative to the carbonyl group was isolated. The resulting chiral spiro[2.5]octanones induce a helical supramolecular ordering in the nematic mesophase of 4-pentyl-4′-cyanobiphenyl and exhibit a twisting power only somewhat (by 20–30%) lower than the starting enones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2331–2341, October, 2005.     

[4+2]-Cyclodimer of sabinone: formation,crystal structure,and NMR spectra

Oxidation of (+)-sabinol, (1S,3R,5S)-1-isopropyl-4-methylidenebicyclo[3.1.0]hexan-3-ol, by active MnO₂ afforded not the expected sabinone but only its [4+2]-cyclodimer. The molecular structure of the latter was established by X-ray diffraction analysis. The ¹H and ¹³C NMR spectra of this cyclodimer were interpreted using 2D NMR spectroscopy.     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphan-Azodicarbonsäureester, 5. Mitt.: Transformationen an Glykonolactonen

Reaction ofD-glucono-1,5-lactone1 with two equivalents oft-butyldimethylchlorosilane yields via a ringcontraction 2,6-bis-O-(t-BDMSi)-D-glucono-1,4-lactone2a as main product and a small amount of 5,6-bis-O-(t-BDMSi)-D-glucono-1,4-lactone2c. Under the same conditionsL-mannono-1,4-lactone3 is transformed to the derivatives 2,6-bis-O-(t-BDMSi)-L-mannono-1,4-lactone3a and 3,6-bis-O-(t-BDMSi)-L-mannono-1,4-lactone3c as the minor product. 2,6-bis-O-(t-BDMSi)-D-galactono-1,4-lactone4a and 2,6-bis-O-(t-BDMSi)-D-gulono-1,4-lactone5a are also prepared from the corresponding glyconolactones4 and5. Whereas the compounds2a, 2c, 4a and5a withAc ₂O-pyridine give the bisacetylderivatives2b, 2d, 4b and5b, 3c is converted by an accompanying migration of one silylgroup to the 5,6-bis-O-(t-BDMSi)-2,3-bis-O-acetyl-L-mannono-1,4-lactone3d. The gluconolactone derivative2a reacts easily withTPP/DEAD/HX to the 5-X-L-idono-1,4-lactone derivatives6a (X=N₃),6b (X=p-NO₂-C₆H₄COO) and6c (3-O-acetylderivative of6a). Treating6b with a second equivalentTPP/DEAD/HX leads to the unsaturated sugarlacton7b. Without an external nucleophile2a affords withTPP the mixture of 2,6-bis-O-(t-BDMSi)-3,5-carbonato-D-glucono-1,4-lactone2c, 3,5-anhydro-L-idono-1,4-lactone8 and 3,6-anhydro-D-glucono-1,4-lactone9. Analogous procedures applied to4a yield theL-altronolactonoderivatives10a, 10b and10c, the unsaturated sugarlactone11b on the one and the 3,5-carbonatogalactonolactone4c and the 2,6-bis-O-(t-BDMSi)-3-desoxy-5-ethoxycarbonyl-D-threo-hex-2-en-1,4-lactone12 on the other hand.Whereas the bis-silyletherderivative3a is transformed by the title system exclusively by an elimination process to13, the derivative5a affords withTPP/DEAD without any elimination the 3,6-anhydrosugar14. Partial desilylation of14 followed by acetylation gives the derivatives14a and14b.Structural elucidations were achieved by¹H-NMR-analysis. In some cases also CD-measurements allowed suitable correlations.

Mark, E., Zbiral, E., Brandstetter, H. H., 4. Mitt., Mh. Chem.111, 289 (1980).