Synthese von 3-(2,4,5-Trihydroxyphenyl)-DL-alanin

Condensation of 2.4.5-trimethoxybenzaldehyde with hydantoin followed by catalytic hydrogenation gave 5-(2.4.5-trimethoxybenzyl)-hydantoin, which was converted to 3-amino-3.4-dihydro-6.7-dihydroxycoumarin by treatment with hydrobromic acid. Hydrolysis of the lactone led to 3-(2.4.5-trihydroxyphenyl)-DL -alanine.     

Synthese und Kristallstruktur von (PPh4)2Se6

Synthesis and Crystal Structure of (PPh₄)₂Se₆ (PPh₄)₂Se₆ has been prepared by the reaction of selenium with K₂Se₂ in dimethylformamide solution in the presence of K₃[Mn(CN)₆] and PPh₄Br, forming black crystal needles. According to the crystal structure determination the compound consists of PPh⁺₄ ions and chainlike hexaselenide ions. Space group P6 , Z = 2,4683 Observed unique reflections, R = 0.066. Lattice dimensions at ?90°C: a = 951.0, b = 1094.8, c = 2137.4 pm, α = 82.66°, β = 83.36°, γ = 89.96°.     

Synthese von 2- und 3-(1,2,3,6-Tetrahydropyridyl)-indolen

The synthesis of a series of 2- and 3-(1,2,3,6-tetrahydro-4-pyridyl)-indoles by reduction of the corresponding pyridinium compounds with sodium borohydride is described. A substantially improved mode of preparation for 3-(4-pyridyl)-indole is given.     

Totalsynthese von Decarboxybetalainen durch photochemische Ringöffnung von 3-(4-Pyridyl)alanin

Total Synthesis of Decarboxybetalaines by Photochemical Ring Opening of 3-(4-Pyridyl)alanine A photochemical approach is presented for the total synthesis of the decarboxybetalaines, which were previously known from the mild decarboxylation of the natural plant colorants, the betalaines: Irradiation of rac-3-(4-pyridyl)alanine ( 1 ) yielded the rac-2-decarboxybetalamic-acid-imine ( 4 , 86%), presumably via a Dewar pyridine 2 , a cyclic aminal 3 and an electrocyclic ring opening. The imine-zwitterion 4 was treated with three amines, namely (S)-cyclodopa ( 6 ), (S)-proline ( 7 ), and indoline ( 8 ), to afford three decarboxybetalaines, namely (2S)-17-decarboxybetanidine ( 9 , red, 34%), (2S)-13-decarboxyindicaxanthine ( 10 , yellow, 56%), and rac-16-decarboxyindobetalaine ( 11 , orange, 78%), respectively. The structures of these coloring matters were confirmed by their electrophoretic behavior and their spectroscopic properties. 17-Decarboxybetanidine 9 was shown to be a ca. 1:1 mixture of two C(15)-epimers 9a and 9b , separable by chromatography. The configuration of 9a was determined as (2S, 15S) and that of 9b as (2S, 15R), by correlating their optical rotations with those of betanidine ( 12a ) and isobetanidine ( 12b ), respectively. The decarboxybetalaines 9 , 10 , and 11 did not show the double-bond isomerism at C(β), (Cγ) of the chromophore which had been found characteristic for the corresponding betalaines 12 , 13 , and 14 .     

Synthese und Kristallstruktur von NaPr2F3(SO4)2

Synthesis and Crystal Strucure of NaPr₂F₃(SO₄)₂ Light green single crystals of NaPr₂F₃(SO₄)₂ have been obtained by the reaction of Pr₂(SO₄)₃ and NaF in sealed gold ampoules at 1050 °C. In the crystal structure (monoclinic, I2/a, Z = 4, a = 822.3(1), b = 692.12(7), c = 1419.9(2) pm, β = 95.88(2)°) Pr³⁺ is coordinated by four F^– ions and six oxygen atoms which belong to five SO₄^– ions. Thus, one of the latter acts as a bidentate ligand. The [PrO₆F₄] units are connected via three common fluoride ions to pairs with a Pr–Pr distance of 386 pm. Na⁺ is sevenfold coordinated by three fluorine and four oxygen atoms.     

Synthese von 4-Hydroxy-3-(2-imidazolyl)-cumarinen

Ohne ZusammenfassungHerrn Prof. Dr.E. Ziegler zum 60. Geburtstag gewidmet.     

Synthese von 4-Benzylthio- und 4-(Arylthio)-1,3-oxazol-5(2H)-onen

Synthesis of 4-(Benzylthio)-and 4-(Arylthio)-1,3-oxazole-5(2H)-ones Following a known procedure, 4-(benzylthio)-1,3-oxazol-5(2H)-one ( 4a ) was synthesized starting from sodium cyanodithioformate ( 1 ) and cyclohexanone (Scheme 1). The structure of the intermediate 4-(benzylthio)-1,3-thiazol-5(2H)-one ( 3a ) was established by X-ray crystallography. An alternative route was developed for the synthesis of 4-(arylthio)-1,3-oxazol-5(2H)-ones which are not accessible by the former reaction. Treatment of ethyl cyanoformate ( 5 ) with a thiophenol in the presence of catalytic amounts of Et₂NH and TiCl₄, followed by addition of a ketone and BF₃.Et₂O in a one-pot-reaction, gave 4f–i in low-to-fair yields (Scheme 3). Both synthetic pathways-complementary as for benzyl–S and aryl-S derivatives–seem to be limited with respect to variation of substituents of the ketone.     

Synthesis of the Ethyl Esters of 4-(3-Pyridyl)- and 4-(4-Pyridyl)-2-oxobutenoic Acids

We have developed a method for the synthesis of ethyl 4-(3-pyridyl)- and 4-(4-pyridyl)-2-oxobutenoates by condensation of 3-pyridinecarbaldehyde and 4-pyridinecarbaldehyde monohydrate respectively with ethyl pyruvate, esterifiction of the target acids, and hydrolysis of the corresponding ethyl ester ketals in the presence of FeCl₃·6H₂O.     

Synthese und Umlagerungsreaktionen von 2-(2-Amino-anilino)-2-imidazolin-Derivaten

The nitro-imidazolines V and VI are formed by addition reaction of ethylenediamine to the isothiocyanates III and IV. The nitro group is then converted by hydrogenation to the amino group, giving XI and XII, which can be acylated selectively to IX and X. By rearrangement in boiling xylene, the compounds XI and XII give the corresponding 2-(2-aminoethylamino)-benzimidazoles XIII and XIV. The benzoylated derivative IX gives the benzimidazole derivative XVIII by rearrangement and subsequent migration of the benzoyl group, while the benzylated derivative XVI gives the rearranged benzimidazole XXII. The benzimidazole structure of the rearranged products is proven by unambiguous synthesis of XIII, starting with 2-chlorobenzimidazole (VII) and mono-N-acetyl-ethylene-diamine to give compound VIII, from which XIII is obtained by hydrolysis.     

Synthese und Kristallstruktur von CsAu(SO4)2

Synthesis and Crystal Structure of CsAu(SO₄)₂ Light yellow single crystals of CsAu(SO₄)₂ were obtained upon evaporation of a solution of Au(OH)₃ and Cs₂SO₄ in sulfuric acid (96 % H₂SO₄). In the crystal structure (monoclinic, P2₁/c, Z = 4, a = 1029.7(2), b = 893.4(2), c = 901.0(1) pm, β = 111.08(1)°) Au³⁺ is in square planar coordination of oxygen atoms which belong to four SO₄^— ions. According to [Au(SO₄)_4/2]^— puckered layers are formed which are connected by the Cs⁺ ions. The latter are surrounded by five chelating and three monodentate sulfate groups leading to a CN of 13.     

Synthese und Kristallstruktur von [Cr(NH3)6][Cr(NH3)2F4][BF4]2

Synthesis and Crystal Structure of [Cr(NH₃)₆][Cr(NH₃)₂F₄][BF₄]₂ The action of ammonium fluoride on a mixture of boron and chromium in a sealed Monel ampoule at 300 °C yields single crystals of [Cr(NH₃)₆][Cr(NH₃)₂F₄][BF₄]₂. The crystal structure (tetragonal, P4/mbm, Z = 2, a = 1056.0(1), c = 781.7(1) pm; R₁ = 0.0414; wR₂ = 0.1087 for 411 reflections with I₀ > 2σ(I)) contains [Cr(NH₃)₆]³⁺ and [Cr(NH₃)₂F₄]^– octahedra and twice as many [BF₄]^– tetrahedra that are arranged in a quadrupled super‐structure of the CsCl‐type of structure.     

Synthese und Kristallstruktur von Sr2Zn(OH)6 und Ba2Zn(OH)6

Synthesis and Crystal Structure of Sr₂Zn(OH)₆ and Ba₂Zn(OH)₆ Crystallization from supersaturated sodium hydroxozincate solutions by adding solutions of alkali earth metal hydroxides yields crystals of Sr₂Zn(OH)₆ and Ba₂Zn(OH)₆. The X-ray structure determination on these crystals was successful including all hydrogen positions: Sr₂Zn(OH)₆: P2₁/n, Z = 2, a = 5.794(1) Å, b = 6.160(1) Å, c = 8.141(1) Å, b = 91.23(1)°, N(F ³° 2σ F) = 1127, N(Var.) = 53, R₁/wR₂ = 0.047/0.081Ba₂Zn(OH)₆: P2₁/n, Z = 2, a = 6.043(1) Å, b = 6.336(1) Å, c = 8.451(2) Å, b = 91.23(2)°, N(F ° 2σ F) = 1669, N(Var.) = 54, R₁/wR₂ = 0.029/0.067. Sr₂Zn(OH)₆ and Ba₂Zn(OH)₆ crystallize isotypic in a distorted Li₂O structure type. Sr²⁺ resp. Ba²⁺ form a cubic primitive arrangement. Distorted octahedra of OH^– around Zn²⁺ fill therein alternating cubic gaps in an ordered way.     

3-(2-Pyridyl)coumarins

3-(2-Pyridyl)coumarins were prepared by reaction of substituted salicylaldehydes and 2-pyridylacetonitrile. Benzylation, acylation, and aminomethylation of 7-hydroxy-3-(2-pyridyl)coumarin was studied. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 428–431, September–October, 2005.     

Synthese und Strukturbestimmung von (i-Pr)2NB(t-BuP)3 und (i-Pr)2NB(t-BuP)4

Synthesis and Structure Analysis of (i-Pr)₂NB(t-BuP)₃ and (i-Pr)₂NB(t-BuP)₄ The diphosphide K(t-Bu)P-(t-BuP)₂-P(t-Bu)K obtained by the cleavage reaction of the 3-membered ring system (i-Pr)₂BN(t-BuP)₂ with potassium reacts with t-BuPCl₂ at ?78°C under ring expansion to form the P₃B ring system (i-Pr)₂NB(t-BuP)₃ – 1,2,3-tri-t-butyl-tri-phospha-4-diisopropyl-aminoboretane ( 1 ). – The 5-membered P₄B ring system (i-Pr)₂NB(t-BuP)₄ – 1,2,3,4-tetra-t-butyl-tetraphospha-5-diisopropylaminoborolidine, ( 2 ) – is formed from K(t-Bu)P? (t-BuP)₂? P(t-Bu)K and (i-Pr)₂NBCl₂ analogous to the above reaction. 1 and 2 could be obtained in a pure form and characterized NMR spectroscopically and by X-ray structure analysis. 1 shows at 200 K two conformation isomers; for 2 ³¹P-^10,11B-isotopic shifts could be identified.     

Synthese und Kristallstrukturen von Quecksilber(II)-iodid-Komplexen mit 3- und 4-pyridylmethylamino- sowie 4-pyridylmethoxy-substituierten Cyclophosphazen-Liganden

Synthesis and Crystal Structures of Mercury(II) Iodide Complexes with 3- and 4-Pyridylmethylamino- and 4-Pyridylmethoxy Substituted Cyclophosphazene Ligands Multifunctional cyclophosphazene ligands with 2-, 3-, and 4-pyridylalkylamino- or 4-pyridylmethoxy groups, N₃P₃(OC₆H₅)₅(NHCH₂(C₅H₄N-2)) ( 1 ), N₃P₃(OC₆H₅)₅ · (NHCH₂(C₅H₄N-3)) ( 2 ), N₃P₃(OC₆H₅)₅(NHCH₂(C₅H₄N-4)) ( 3 ) and N₃P₃(OC₆H₅)₅(OCH₂(C₅H₄N-4)) ( 4 ) are accessible through reactions of monochlorpentaphenoxycyclotriphosphaza-1,3,5-trien with aminomethylpyridine or pyridyl methanolate. 1 does not react with mercury(II) iodide whereas 2–4 yield the metal complexes 2 a , 3 a , and 4 a by interactions of the pyridyl nitrogen atoms. The X-ray single crystal structure analyses of these compounds shows that 2 a and 4 a are dimers, whereas 3 a is a HgI₂ polymer with syndiotacticaly arranged ligands.     

Die Einwirkung von Ammoniumfluorid auf Scandium: Synthese und Kristallstrukturen von (NH4)3[ScF6] und [Cu(NH3)4]3[ScF6]2

Action of Ammonium Fluoride on Scandium: Synthesis and Crystal Structures of (NH₄)₃[ScF₆] and [Cu(NH₃)₄]₃[ScF₆]₂ The action of (NH₄)F on scandium in copper ampoules yields either (NH₄)₃[ScF₆] or ScF₃ and a small quantity of [Cu(NH₃)₄]₃[ScF₆]₂, respectively, depending upon the molar ratio of the educts (NH₄)F : Sc (6 : 1 and 4 : 1, respectively) and temperature. (NH₄)₃[ScF₆] crystallizes with the cryolite type of structure: monoclinic, P2₁/n, Z = 2; a = 650.0(2); b = 651.4(2); c = 949.0(2) pm; β = 90.40(2)°, [Cu(NH₃)₄]₃[ScF₆]₂ is triclinic, P‐1, Z = 1; a = 821.1(2); b = 821.2(2); c = 822.7(2) pm; α = 90.04(3); β = 90.00(3); γ = 90.16(3)°. In its chemical behaviour against (NH₄)F, scandium parallels aluminium rather than gallium.     

Synthese und Kristallstruktur von (Ph3PNPPh3)2[Cu(N3)4]

Inhaltsübersicht. Die Titelverbindung entsteht neben CuN₃ · PPh₃ bei der Einwirkung von Natriumazid auf CuCl₂ und Triphenylphosphan in siedendem Acetonitril bei Anwesenheit von 15-Krone-5 als Lösungsvermittler für NaN₃. (Ph₃PNPPh₃)₂[Cu(N₃)₄] bildet schwarze Kristalle, die wir durch das IR-Spektrum und durch eine röntgenographische Strukturanalyse charakterisiert haben. Raumgruppe Pbca, Z = 4, (4245 beobachtete unabhängige Reflexe, R = 7,2%), Gitter-abmessungen (20°C):a = 1980, 1;b = 1618,8; c = 2014,3 pm. Die Verbindung besteht aus Kationen [Ph₃PNPPh₃]⁺ und Anionen [Cu(N₃)₄]^2– der Symmetrie C_i, in denen das Cu-Atom planar von den α-N-Atomen der Azidgruppen mit Cu–N-Abständen von 197,2(4) und 189,5(4) pm umgeben ist. Synthesis and Crystal Structure of (Ph₃PNPPh₃)₂[Cu(N₃)₄] The title compound is prepared besides CuN₃ · PPh₃ by the reaction of sodium azide with CuCl₂ and PPh₃ in boiling acetonitrile in the presence of 15-crown-5. (Ph₃PNPPh₃)₂[Cu(N₃)4] forms black crystals, which have been characterized by their IR spectrum as well as by an X-ray structure determination. Space group Pbca, Z = 4 (4245 observed independent reflexions, R = 0.072), lattice dimensions (20°C): A = 1980.1; b = 1618.8; c = 2014.3 pm. The compound consists of Ph₃PNPPh₃⁺ cations and anions [Cu(N₃)₄]^2– with symmetry C₁, in which the copper atom is planarly surrounded by the four nitrogen atoms of the azide groups with bond lengths Cu–N of 197.2(4) and 189.5(4) pm, respectively.     

Synthese und Struktur von (Ph3PAu)3Mn(CO)4

Synthesis and Structure of (Ph₃PAu)₃Mn(CO)₄ Photolysis of (Ph₃PAu)Mn(CO)₅, Ph₃PAuN₃ and Ph₃PAuNCO yields (Ph₃PAu)₃Mn(CO)₄ ( 1 ). 1 crystallizes in the monoclinic space group P2₁/n with a = 1 031.3(1); b = 3 095.2(3), c = 3 386.3(3) pm; β = 97.58(3)°; Z = 8. The crystal structure contains two symmetry independent clusters 1 of the same geometry. Their inner core MnAu₃ forms a rhombus with distances Mn? Au of about the same lengths between 258.4(4) and 262.0(4) pm. The distances Au? Au range from 276.6(2) to 281.3(2) pm. The bonding in 1 is discussed and compared with those of (Ph₃PAu)₃Co(CO)₃ having the same total number of electrons but a tetrahedral framework.     

Claisen-Umlagerung von 2-Propinyl-(3-pyridyl)-und Allyl-(3-pyridyl)äthern

Claisen Rearrangement of 2-Propinyl (3-Pyridyl) and Allyl (3-Pyridyl) Ethers

1 Verbindungen vom Typ 1 werden mit Ausnahme von 17 und 25 als Äther benannt. Der systematische Name von 1 ist: 3-(2-Propinyl)oxy-pyridin.

2-Propinyl (3-pyridyl) ether ( 1 ), synthesized from the corresponding 3-pyridinol, was heated in DMF or decane at 208° in a sealed tube. In this way the furopyridines 2 and 3 were formed, and furthermore the pyranopyridine 4 if decane was used as solvent (Scheme 1). The same reactions took place with (2-methyl-3-pyridyl) 2-propinyl ether ( 14 ). In DMF only 15 , and in decane 16 as well as 15 were formed (Scheme 3). The rearrangement of the pyridine derivative 17 , which is substituted in both O-positions to the ether moiety, gave in both DMF and decane the diastereoisomeric tetracyclic compounds 18 and 19 . The same kind of reaction took place with 25 (Scheme 4). In the thermolysis of the allyl 3-pyridyl ether ( 27 ) cyclization was observed, too. The isolated product has the structure of the dihydrofuropyridine 28 (Scheme 6). The substituted allyl 3-pyridyl ether 30 reacted in the same way to the dihydrofuropyridine 31 (Scheme 6).