bluuebunny/crossref_metadata_2025 huggingface dataset:
3,4‐Dimethylenborolane und 3,7‐Diborabicyclo[3.3.0]oct‐1(5)‐ene
Authors: Herberich Gerhard E. , Eigendorf Uwe , Englert Ulli
Published: July 2007

3,4‐Dimethyleneborolanes and 3,7‐Diborabicyclo[3.3.0]oct‐1(5)‐enes

The tetramethyleneethane derivative K2[C2(CH2)4] which is readily prepared from 2,3‐dimethylbutadiene by metallation with the Lochmann‐Schlosser base reacts with BC12(NR2) (RMe, Et, iPr) to give the highly reactive, liquid 1‐(dialkylamino)‐3,4‐dimethyleneborolanes (3). These dienes react with activated magnesium to give soluble magnesium adducts 5 which upon treatment with BC12(NR2) (R = Me, iPr) yield crystalline 3,7‐bis(dialkylamino)‐3,7‐diborabicyclo‐[3.3.0]oct‐1(5)‐enes (4). The crystal structure of the dimethyl‐amino compound 4a was determined by X‐Ray‐diffraction. The molecule of 4a shows crystallographic C2h symmetry with an almost perfectly planar skeleton.
Iron‐Catalyzed Coupling of Tricyclo[4.1.0.02,7]hept‐1‐ylmagnesium Bromide and Related Grignard Reagents with Propargylic and Allylic Halides
Authors: Hashmi A. Stephen K. , Szeimies Günter
Published: July 2007

Several uncatalyzed and transition metal‐catalyzed cross coupling reactions of the Grignard compounds 1c or 2c with propargylic or allylic halides were investigated. Fe(acac)3 was the most effective catalyst for the preparation of allyl‐and propargylbicyclo[1.1.0]butanes 7 and 5. In the latter case, the formation of the isomeric allenylbicyclo[1.1.0]butanes 6 was also observed. Stereoelectronic factors of substituents like a trimethylsilyl group as a directing group could be utilized for the formation of either 5 or 6. A number of bicyclo[1.0.0]butanes 15–21 with two substituents in the bridgehead positions were accessible by that route as well. In the case of the bis‐allenyl compound 24c, an ene‐type reaction leading to the first known derivative of a [4.1.1]propella‐2,4‐diene 25 was observed. Base‐catalyzed isomerizations of the propargylbicyclo[1.1.0]butanes 5 opened a new route to alkynylbicyclo[1.1.0]butanes 30–32.
Structure of Octamethylene‐Bridged Derivatives of 1,3‐Cyclohexadiene and Bicyclo[3.1.0]hexene
Authors: Irngartinger Hermann , Oeser Thomas , Jahn Reiner
Published: July 2007

Synthesis and photochemical generation of the octamethylene‐bridged 1,3‐cyclohexadiene and bicyclo[3.1.0]hexene derivatives 1 and 2, which are to be classified as anti‐Bredt olefins, are reported. out Orientation of the octamethylene bridge at the sp3‐hybridized bridgehead atom of 1 generates strain effects while in orientation of the bridge in 2 does not give rise to deformations of the bicyclo[3.1.0]hex‐2‐ene subunit. X‐ray analyses indicate a twisted double bond (12.2 and 15.0°) at the bridgehead atom of 1 and a deformation of the six‐membered ring from an ideal boat conformation. In contrast, the five‐membered ring of compound 2 is planar. The folding angle between the five‐ and the three‐membered ring is 111.8(2)°. The olefinic carbon atoms of 1 are slightly pyramidalized.
Syntheses of Zindoxifene and Analogues by Titanium‐Induced Oxo‐Amide Coupling
Authors: fürstner Alois , Jumbam Denis N. , Seidel Günter
Published: July 2007

Highly reactive titanium on graphite is used to reductively cyclize electron‐rich acylamino carbonyl compounds 7, 8, 12, 14, and 16 to the corresponding indole derivatives 9, 10, 13, 15, and 17. Compound 9b is a known precursor of the mammary tumor‐inhibiting compound zindoxifene (2). The other products are new analogues of this anticancer drug, exhibiting the substitution pattern previously recognized to be essential for high pharmacological activity.
Darstellung, Struktur und konformatives Verhalten gespannter Adamantanophane
Authors: Lemmerz Ralf , Nieger Martin , Vögtle Fritz
Published: July 2007

Preparation, Structure, and Conformational Behaviour of Strained Adamantanophanes

Exchange of aromatic units (e.g. benzene) for aliphatic/alicyclic building blocks (e.g. adamantane) in cyclophanes leads to new molecules of the “araliphane” type. In the framework of this concept the araliphanes 3(a), 5–7a, 10(a), and 11 are synthesized. Their stereochemical behaviour differs significantly from that of their aromatic counterparts as shown by NMR studies and X‐ray crystallographic analyses. Extremely upfield‐shifted signals of the intraanular adamantane hydrogen atoms are found as well as a planar chiral adamantanophane. A Diels‐Alder addition of 8 to the benzene ring of 6 yields 9. Complete replacement of benzene units by adamantane leads to the fully aliphatic/alicyclic “aliphanes”. The crystal structure of 15 is described.
Chelat‐stabilisierte 1,3‐Bis(acyloxy)‐1,3‐diethyldiboroxane aus Triethylboroxin und Carbonsäureanhydriden
Authors: Köster Roland , Sporzyński Andrzej , Schüßler Wilhelm , Bläser Dieter , Boese Roland
Published: July 2007

Chelate‐Stabilized 1,3‐Bis(acyloxy)‐1,3‐diethyldiboroxanes from Triethylboroxin and Carboxylic Acid Anhydrides

Triethylboroxin (A) reacts with carboxylic acid anhydrides (RCO)2O [R = Me: 1a; Et: 1b; tBu: 1d; Ph: 1e] with various rates to give high yields of the 3,7‐dialkyl‐1,5‐diethyl‐4,8,9‐trioxa‐2,6‐dioxonia‐1,5‐diboratabicyclo[3.3.1]nona‐2,6‐dienes OB(Et)OC(R)OB(Et)OC(R)O (2) [R = Me: 2a (X‐ray crystal structure analysis); Et: 2b; tBu: 2d; Ph: 2e], presumably via the unstable compounds OB(Et)OB(Et)OC(R)OB(Et)OC(R)O (3a,b, d, e). Compound 1c (R = CF3) reacts with A to form a mixture of 1,3‐diethyl‐1,3‐bis(trifluoroacetoxy)diboroxane OC(CF3)OB(Et)OB(Et)O(CF3)CO (2c′) and 2c (R = CF3) at room temperature. Whereas two compounds of the type 2 do not comproportionate, 1a–e spontaneously form the mixed substituted carboxylic acid anhydrides 1ab etc. on mixing at room temperature (GC, 13C NMR). ‐ From the 17O‐enriched A* and 1a–e the 17O‐enriched compounds 2a*‐e* with BO*B and YYBO*OCR groups are obtained. A* exchanges O atoms up to 200°C with succinic anhydride (1f) forming 1f* or with phthalic acid anhydride (1g) forming 1g* and 3g*. ‐ The mixed carboxylic acid anhydrides 1xy are cleaved, and the mixtures of 1 are separated with A to yield the uniform 3,7‐dialkyl‐substituted compounds 2.
Zinkkomplexe von Aminosäuren und Peptiden, 4. Zinkkomplexe von Peptiden mit C‐terminalem Cystein
Authors: Meißner Axel , Gockel Peter , Vahrenkamp Heinrich
Published: July 2007

Zinc Complexes of Amino Acids and Peptides, 4. ‐ Zinc Complexes of Peptides with C‐terminal Cysteine

The cysteine derivatives N‐Ac‐Cys, N‐Ac‐Gly‐Cys, N‐Ac‐Ala‐Cys, and N‐Ac‐Gly‐Gly‐Cys with unprotected SH and CO2H functions (LH2) were prepared by the mixed anhydride method. Their reactions with basic zinc carbonate resulted in the formation of complexes Zn(LH)2 which were converted by KOH to complexes K2[ZnL2]. Potentiometric titrations revealed ZnL and [ZnL2]2− as the major solution species. By pD‐dependent NMR measurements (1H, 13C) in D2O carboxylate coordination in acidic solution and carboxylate and thiolate coordination in neutral and basic solution was identified.
Cycloadditionen Organometallfragment‐substituierter Alkene, I. [3 + 2]‐Cycloaddition von η1‐Allyl‐Eisenkomplexen mit Nitriloxiden: Ferriomethyl‐substituierte Isoxazoline
Authors: Malisch Wolfgang , Züller Jürgen , Schwarz Marietta , Jäger Volker , Arif Atta M.
Published: July 2007

Cycloadditions of Organometal Fragment‐Substituted Alkenes, I. ‐ [3 + 2] Cycloaddition of η1‐Allyl Iron Complexes with Nitrile Oxides: Ferriomethyl‐Substituted Isoxazolines

The isoxazolines C5H5(OC)(L)Fe‐CH2‐CH‐CH2‐C(R) = N‐O (3a–f) [R = Ph, 2,4,6‐Me3C6H2; L = CO, P(OCH2)3CCH3, PPh3], substituted with a ferriomethyl group in 5‐position, are obtained by 1,3‐dipolar cycloaddition of the η1‐allyliron complexes C5H5(OC)(L)Fe‐CH2‐CH=CH2 [L = CO (1a), P(OCH2)3CCH3 (1b), PPh3 (1c)] with the nitrile oxides RCNO [R = Ph (2a), Mst (2b)]. The chiral complexes 1b, c produce the diastereomeric isoxazolines 3b, c, e, f with diastereomer ratios of 59:41 to 93:7. The structure of 3d is established by crystal structure analysis.
Structure of the cis and trans Isomers of 2,4‐Bis(diethylamino)‐1,5‐dimethyl‐1,5,2,4‐diazadiphosphorinan‐6‐one 2,4‐Disulfide
Authors: Shevchenko Igor V. , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

The 2,4‐bis(dialkylamino)‐1,5‐dimethyl‐1,5,2,4‐diazadiphos‐phorinan‐6‐ones 1a and 1b (R = CH3, a; C2H5, b) are thermally unstable and are transformed into the bicyclic species 2 when heated to 150°C (2 Torr). The reactions of 1a and 1b with elemental sulfur lead to the P,P′‐disulfides 4a and 4b as a mixture of cis and trans isomers which are separated by column chromatography. Single‐crystal X‐ray structure determinations were conducted on compound 2 and on the cis and trans isomers of 4b. The bicyclic compound 2 is found to display crystallographic twofold symmetry. Its structure is closely similar to that of the diphenyl analogue. For the cis and trans isomers of 4 almost ideal S‐P…P‐S torsion angles are observed. The isomers adopt different ring conformations.
Coronene‐Potassium(THF)2(tmeda): X‐Ray Structure and MNDO Calculations of a Half‐Sandwich Contact Ion Pair as a Model for Potassium(Adsorbate)‐Graphite Surface Interactions
Authors: Janiak Christoph , Hemling Holger
Published: July 2007

Crystallization of potassium(1+) and the radical ion coronene(1‐) from a mixture of tetramethylethylenediamine (tmeda), tetrahydrofuran (THF), and diethyl ether yields a monomeric solvated ion pair 1 with potassium unsymmetrically π‐coordinated to an external ring of the polyaromatic system according to an X‐ray structure determination and in agreement with a MNDO theoretical investigation.
Synthese mittlerer und großer Ringe, XXXVI. Synthese eines überbrückten, in‐konfigurierten Bicyclo[2.1.0]pentan‐Derivates
Authors: Tochtermann Werner , Sdunnus Norbert , Wolff Christian , Reggelin Michael
Published: July 2007

Synthesis of Medium and Large Rings, XXXVI. — Synthesis of a Bridged Bicyclo[2.1.0]pentane Derivative with inside Configuration

Dihydrocyclobutafurans 4 (H instead of Br) are reactive intermediates in the photochemical rearrangement of 3,6‐hexanooxepine‐4,5‐dicarboxylic esters. The synthesis of the bromo derivative 4 was achieved by irradiation of the epoxyoxepine 1 followed by a regio‐ and stereoselective NBS bromination of 2 and deoxygenation of 3 with tungsten hexachloride/n‐butyllithium. Treatment of the allylic bromide 4 with sodium methoxide gave surprisingly the title compound 5. The structure of 5 was established by thorough NMR analysis.
Reactivity of Imines Towards 3‐Trifloxypropeniminium and Propyniminium Triflates
Authors: Rahm Rainer , Maas Gerhard
Published: July 2007

The imines 5 and 11 react with 3‐trifloxypropeniminium triflates 1a–d to afford the heterocyclic iminium salts 8, 9, 13, 15, and 17, respectively, or the propeniminium salt 21. Propyniminium triflates 22, 24 react with imines by initial conjugated addition, followed by a reaction sequence analogous to the one observed for the reactions of 1a–d with imines. Thus, salt 22 and aldimine 5b yield the propeniminium salt 21, while 24 reacts with tri‐tert‐butylazete 25 to afford the semicyclic vinamidinium salt 28. A crystal structure analysis of 28 is performed.
Synthesis and X‐Ray Structures of New Macrocyclic Thioethers
Authors: Mlinarić‐Majerski Kata , Pavlović DražEn , Luić Marija , Kojić‐Prodić Biserka
Published: July 2007

4,6:12,14‐Di(1,3‐adamantano)‐1,9‐dithiacyclohexadecane (1), 4,6:12,14:20,22‐tri(1,3‐adamantano)‐1,9,17‐trithiacyclotetracosane (2), and 5,7:14,16‐di(1,3‐adamantano)‐1,2,10,11‐tetrathiacyclooctadecane (3) have been obtained by intermolecular cyclization of 1,3‐bis(2‐bromoethyl)adamantane (4) with thioacetamide using a high‐dilution technique. The reaction is concentration‐dependent. The crystal structures of 1, 2, and 3 have been determined by single‐crystal X‐ray diffraction.
Ein neuer Zugang zu 1,2‐ und 1,3‐Diborol
Authors: Gabbert Gernot , Pritzkow Hans , Kaschke Michael , Siebert Walter
Published: July 2007

A New Approach to 1,2‐ and 1,3‐Diborole

Herrn Prof. Dr. Joachim Knappe zum 65. Geburtstag gewidmet.

Diaminoborylation of 1,3‐dilithiopropenes leads to the (Z)‐1,3‐bis(diaminoboryl)propenes 4a, b, which are transformed by an amine/chlorine exchange to the (Z)‐1,3‐bis(aminochloroboryl)propenes 5a, b. These react with sodium to yield the 2,5‐dihydro‐1H‐1,2‐diboroles 2c, d, whereas the reaction with potassium leads to the 2,3‐dihydro‐1H‐1,3‐diboroles 6a, b by rearrangement of the C3B2 skeleton. The constitutions of the heterocycles 2c, d and 6a, b are established by X‐ray structure analyses. Reaction of the 1,2‐diboroles 2c, d with (C5H5)Co(C2H4)2 leads to the red (1‐borabutadiene)cobalt complexes 3c, d. In 3c a sigmatropic rearrangement is studied by NMR spectroscopy.
2‐Chloro‐2‐phenyl‐2‐(p‐tolylthio)‐1,3‐diorgano‐1,3,2λ5‐diazaphosphetidin‐4‐ones
Authors: Pinchuk Vasily A. , Neda Ion , Müller Christian , Fischer Axel , Jones Peter G. , Shermolovich Yuri G. , Schmutzler Reinhard
Published: July 2007

The reaction of N,N′‐dimethyl‐N,N′‐bis(trimethylsilyl)urea (1) or N‐methyl‐N′‐phenyl‐N,N′‐bis(trimethylsilyl)urea (2) with p‐toluenesulfenyl chloride furnished N,N′‐dimethyl‐N‐(p‐tolylthio)‐N′‐
Synthesis and Stereochemistry of Chiral Macrocycles Including a 1,2‐Bis(phenylphosphanyl)benzene Unit
Authors: Widhalm Michael , Klintschar Gerd
Published: July 2007

The synthesis of the four 1,1′‐binaphthyl‐based macrocyclic bisphosphane ligands 6b–e (racemic and optically active) and their square‐planar cis‐P2‐MCl2 complexes (M = Ni, Pd) is reported. In three cases isomers could be isolated and identified. The absolute and relative stereochemistry of all ligands and complexes was established on the basis of their NMR and CD spectra and finally confirmed by X‐ray structural determinations of selected ligands and complexes.
Festkörper‐13C‐NMR‐Spektroskopie, 1. Titantetrachlorid‐Komplexe von Diketonen: Ihre Bedeutung für Hydrid‐Reduktionen und ihre Festkörper‐NMR‐Spektren
Authors: Maier Güunther , Seipp Ulrich , Kalinowski Hans‐Otto , Henrich Markus
Published: July 2007

Solid‐state 13C‐NMR Spectroscopy, 1. — Titanium Tetrachloride Complexes of Diketones: Their Importance for Hydride Reductions and Their Solid‐State NMR Spectra

Herrn Prof. Christoph Rüchardt zum 65. Geburtstag gewidmet.

The influence of titanium tetrachloride on the diastereoselectivity of hydride reductions of 1,2‐, 1,3‐, 1,4‐ and 1,5‐diketones has been studied. The effect is especially pronounced in the case of 1,3‐diketones, where the addition of titanium tetrachloride reverses the stereoselectivity. The assumption of a chelate of type 32 or 33 can be confirmed by several observations: β‐hydroxy ketone 7 and β‐benzyloxy ketone 9 show the same dependence on the stereochemical course as diketone 5a. This compound forms complex 34, whose conformation is known by X‐ray structure determination. From the solid‐state 13C‐NMR spectra of the TiCl4 adducts it can be deduced that 7 forms chelate 42, which is close to the assumed intermediate 32. In the case of phenyl‐substituted substrates solid‐state 13C‐NMR spectroscopy can also be used to differentiate between real chelates (coordination of TiCl4 at the oxygen atoms of the carbonyl groups) and π complexes.
Highly Substituted 1,3‐Dienes, IV. An Experimental and Theoretical Study of the Stereochemical Properties of 2‐tert‐Butyl‐1,3‐butadiene and 2,3‐Di‐tert‐butyl‐1,3‐butadiene
Authors: Trætteberg Marit , Hopf Henning , Lipka Helmut , Hänel Ralf
Published: July 2007

The molecular structure and conformation of 2‐tert‐butyl‐1,3‐butadiene (1) and of 2,3‐di‐tert‐butyl‐1,3‐butadiene (2) have been studied by the gas electron diffraction method. The monosubstituted compound is observed to have a gauche orientation (φ = 32°) of the conjugated C=C bonds. The forces determining the preferred conformation of this molecule (syn or gauche) appear to be similar to those operative in the case of the high‐energy conformer of unsubstituted 1,3‐butadiene. The disubstituted compound has an approximately perpendicular orientation of the C=C–C=C system (φ = 101.5°), and in this case the preferred orientation is described as a result of minimalization of the nonbonded interactions. – Theoretical calculations of the structure and conformation of the two molecules have been carried out by molecular mechanics (MM3) and by ab initio (HF/3–21G) methods. The results from both sets of calculations are in good agreement with the observed structures of the two compounds.
Synthesis, Structure and Reactivity of Cyclopenta‐annulated 1,2,3,4‐Tetrazines
Authors: Mackert Peter J. , Hafner Klaus , Nimmerfroh Norbert , Banert Klaus
Published: July 2007

The 2‐aryl‐2H‐cyclopenta[e]‐1,2,3,4‐tetrazines 3a‐n are formed by coupling of the diazocyclopentadienes 1a and 1b with arenediazonium salts and subsequent reversible electrocyclization of the primary coupling products 2a‐n. From the solutions of the equilibrium mixtures of 2a ⇌ 3a ‐ 2n ⇌ 3n the tetrazines 3a‐d, h‐k and the arylazo‐diazocyclopentadienes 2e‐g and 21‐n crystallize. The 2‐methyl‐2H‐cyclopenta[e]‐1,2,3,4‐tetrazines 3o and 3p are obtained by addition of methyllithium to 1a and 1b followed by a diazo transfer reaction and cyclization. In solutions of 3o and 3p the ring‐opened isomers 2o and 2p could not be detected. X‐ray analyses of 3h and 3p prove their bicyclic planar geometry in the solid state. 15N‐NMR and temperature‐dependent 1H‐NMR spectroscopy have enabled a detailed study of the reversible ring closure reaction in the case of 2d ⇌ 3d. Reaction of 2‐phenyl‐2H‐cyclopenta[e]‐1,2,3,4‐tetrazine (3b) with tetrafluoroboric acid results in the formation of the protonated monocyclic salt 4. Furthermore 3b undergoes electrophilic substitution reactions preferably at C‐7, as demonstrated by bromination, formylation, and trifluoroacetylation. Photolysis of solutions of 2i/3i, 2k/3k, and 21/31 leads to the ketene imines 11a‐c. The structure of 11c has been determined by X‐ray crystallography.
Copper‐Catalyzed Conjugate Addition of Trimethylaluminium to α,β‐Unsaturated Ketones
Authors: Kabbara Jazid , Flemming Steffen , Nickisch Klaus , Neh Harribert , Westermann Jürgen
Published: July 2007

The conjugate methylation of α,β‐unsaturated ketones with trimethylaluminium occurs smoothly in a very simple procedure under the catalytic effect of Cu1 salts. Scope and limitations of this process as well as the influence of solvent and catalyst on the kinetics were studied. In addition, the effect of chlorotrimethylsilane as an additive was investigated. Attack on the carbonyl group in 1,2‐fashion could not be observed under the reaction conditions.
Neue 1,6‐Methano[10]annulen‐Derivate mit “parallelen Dreifachbindungen”
Authors: Neidlein Richard , Kux Ulrich
Published: July 2007

New 1,6‐Methano[10]annulene Derivatives with “Parallel Triplebonds”

Herrn Professor Gerhard Fritz zum 75. Geburtstag gewidmet.

Teil der Dissertation von U.K.(Lit.[9c]).

The peri‐ethinyl‐substituted 1,6‐methano[10]annulenes 2–5 were synthesized starting from 1c or 1d. Hydrolysis of 4 yielded 6; compounds 7 and 8 were isolated as undesired side‐products of these syntheses. The interactions between the “parallel triplebonds” were investigated.
Herstellung von 1,5‐Cyclooctadiin und 1,3,5,7‐Cyclooctatetraen aus 1,5‐Cyclooctadien
Authors: Detert Heiner , Rose Bernd , Mayer Winfried , Meier Herbert
Published: July 2007

Preparation of 1,5‐Cyclooctadiyne and 1,3,5,7‐Cyclooctatetraene from 1,5‐Cyclooctadiene

Bromination of 1,5‐cyclooctadiene (1) and stepwise dehydro‐bromination first with KOtBu and then with KOtBu/18‐crown‐6 yields 1,5‐cyclooctadiyne (5). A prolonged interaction of the base causes a complete transformation to cyclooc‐tatetraene (6). Diyne 5 and even more the intermediate enyne 4 are highly reactive dienophiles. The cycloadducts 10–14 formed with 1,3‐cyclohexadiene, carbon disulfide, and tetraphenylcyclopentadienone were isolated and characterized. Treatment of 5 with titanium tetrachloride induces a vigorous polymerization.
Chelating Coordination of Di‐ and Triallylamines: Syntheses and NMR Studies of Trimethylphosphane Nickel and Cobalt Complexes
Authors: Klein Hans‐Friedrich , Helwig Michael , Braun Siegmar
Published: July 2007

16‐Electron complexes of zerovalent nickel with diallylamines, Ni[(C3H5)2NR]L [1, 2: L = P(CH3)3, R = CH3, C6H5; 3: L = P(C6H5)3, R = CH3] and [NiP(CH3)3]2CH2[N(C3H5)2]2 (4), were synthesized by reduction of NiCl2L2 with magnesium in tetrahydrofuran. NiCl(η3‐C3H5)[P(CH3)3]2 (5), a low‐yield byproduct, was also obtained in high yield from NiL4 and C3H5Cl. With triallylamine as starting material complexes Ni[(C3H5)3N]L [6: L = P(CH3)3; 7: L = P(C6H5)3] were generated exhibiting η6‐ and η4‐olefin coordination, respectively. 17‐electron cobalt(O) compounds Co[(C3H5)2NR](PMe3)2 (8, 9: R = CH3, C6H5) were obtained by reaction of Co(cyclo‐C5H8)(PMe3)3 with the corresponding diallylamine, while CoR(PMe3)4 (R = CH3, C6H5) reacted with N,N‐diallylaniline to give diagmagnetic Co[(η3‐C3H4)(η2‐C3H5)NC6H5](PMe3)2, (10). The coordination mode of allylic functions was deduced from IR, ESR and especially 1H‐ and 13C‐NMR spectra including 2D‐NMR experiments.
(Organoboryl)sulfate — Herstellung und Charakterisierung[1]
Authors: Köster Roland , Schüßler Wilhelm , Bläser Dieter , Boese Roland
Published: July 2007

Organoboryl Sulfates — Preparation and Characterisation[1]

Triethylborane (3) reacts with sulfuric acid to form the sulfate Et2BOS(O2)OBEt2 (1a), which can also be prepared from (Et2B)2O (4a) and SO3. Sulfate 1a reacts with (C8H14B)2O (4b) to give the solid sulfate C8H14BOS(O2)OBC8H14 (1b) and 4a. Compound 1b is also obtained by treating 4b with SO3. The reaction of 4a with sulfuric acid leads to the crystalline cyclic sulfate EtBOB(Et)OS(O2)O (2a) (X‐ray structure analysis). 2a is also available from triethylboroxin (5) on reaction with SO3. The diboroxanes 4a and 4b and H2SO4 form insoluble 1:1 addition complexes 4a·H2SO4 and 4b·H2SO4, which react on heating at about 60°C to yield the cyclic sulfates 2a and C8H15BOB(C8H15)OS(O2)O (2b), respectively.
Phosphonium Ylides with Functionalized Silyl Substituents
Authors: Dreihäupl Karl‐Heinz , Angermaier Klaus , Riede Jürgen , Schmidbaur Hubert
Published: July 2007

Two series of aminophosphonium ylides with reactive alkoxychlorosilyl substituents (R2N)3P=CHSi(OR')2Cl (1‐8, R = Me, Et/R' = Me, Et, iPr, tBu) have been prepared by reaction of the aminophosphonium ylides (R2N)3P = CH2 with the corresponding dialkoxydichlorosilanes Cl2Si(OR')2. Substituent effects have been investigated by heteronuclear solution NMR studies of the nuclei 1H, 13C, 15N, 17O, 29Si, and 31P. These studies show an alternating shielding effect along the C–O–Si–C backbone. Further reactions of the chlorosilylated ylides with the aminomethylenephosphorane (Me2N)3P=CH2 lead to the formation of the bis‐ylidic compounds [(Me2N)3P=CH]2Si(OR')2 (9, 10), which are also available in one‐pot syntheses. The molecular structure of [(Me2N)3P=CH]2Si(OiPr)2 (9) has been confirmed by single‐crystal X‐ray diffraction. In the crystal the molecules have two ylidic carbon centers with planar configuration, which are bridged by a nearly tetrahedral silicon atom. Short P–C and Si–C distances indicate a stabilizing effect of the carbanionic centers.
Chemistry of Diborane(4) Derivatives: Mixed Tetraaminodiboranes(4) and Additions of Diborane(4) Derivatives to an Amino‐imino‐borane
Authors: Loderer Dirk , Nöth Heinrich , Pommerening Hans , Rattay Wilfried , Schick Hannes
Published: July 2007

Several transamination reactions of B2(NMe2)4 (1a) with secondary amines have led to mixed tetraaminodiborane(4) compounds B2(NMe2)4 ‐ n(NR2)n (2–4), and B2(NC5H10)4 (1d) has been characterized by an X‐ray structure analysis which reveals the presence of a rather long B–B bond (1.75 Å). However, tetraaminodiboranes(4) of type R2N(Me2N)B‐B(NMe2)NR2 are more readily accessible from LiNR2 and B2(NMe2)2Cl2. Similarly, amination of B2(NMe2)2Cl2 with N,N'‐dimethylethylenediamine (7) yields B‐[bis(dimethyl‐amino)boryl]‐N,N'‐dimethyl‐1,3,2‐diazaborolidine (8), while reactions with Li(Me)N–CH2–CH2–N(Me)Li (9) lead also to 2,3‐bis(dimethylamino)‐1,4‐dimethyl‐1,4,2,3‐diazadiborinane (10) as the kinetically controlled product. This is further substantiated by the reaction of the B2(NMe2)2Br2 with 9 which gives exclusively the corresponding 1,4,2,3‐diazadiborinane 11. Diborane(4) dihalides B2(NMe2)2X2 (X = Cl, Br) react only in a 1:1 ratio with tmp‐B=N‐CMe3 (13) leading to 14a, b. However, both a 1:1 and a 1:2 methoxyboration of 13 has been observed with B2(OMe)4 with formation of 15 and 16.
TaNi2.05Te3, eine Verbindung mit “aufgefüllter” TaFe1+xTe3‐Struktur
Authors: Neuhausen Jörg , Tremel Wolfgang , Evstafyev Vladimir K. , Kremer Reinhard K.
Published: July 2007

TaNi2.05Te3, a Novel Telluride with “Stuffed” TaFe1+xTe3 Structure

The novel metal‐rich layer compound TaNi2.05Te3 was synthesized from the elements. Its structure contains TaNi2Te3 layers which are interconnected by Ni atoms on partially occupied tetragonal‐pyramidal sites located between the layers. The title compound and the related telluride TaFe1.14Te3 form a pair of compounds differing only in the occupation or nonoccupation of one 3d‐material atom site. Therefore, the structure of TaNi2.05Te3, which is stabilized by interstial Ni atoms, can be regarded as a “stuffed” TaFe1.14Te3 type. Pairs of compounds with a similar structural relationship seem to be of general importance in early transition‐metal chalcogenide chemistry. The existence of TaNi2.05Te3 was recently proposed based on the results of extended Hückel band‐structure calculations. TaNi2.05Te3 is a metallic conductor according to the results of four‐probe resistivity measurements.
Pyridinio‐isoalloxazinophanes as Model Systems for Active‐Site Complexes in Flavoenzymes: Syntheses, X‐Ray Structure Analyses and Spectroscopic Properties
Authors: Staab Heinz A. , Zipplies Matthias F. , Müller Thomas , Storch Matthias , Krieger Claus
Published: July 2007

As model systems for active site complexes in flavoenzymes, flavin and nicotinamide analogues were linked together in cyclophane skeletons of specific sterical structures. Elaborating this concept, we prepared [4]metacyclo[3](10,6)isoalloxazinophane (3), [4](3,1)pyridino[3](10,6)isoalloxazinophane (4), as well as the 16‐methoxycarbonyl and the 16‐carboxylato derivatives (2 and 34, resp.), of 4 by multistep syntheses. For the isoalloxazinophanes 2, 3, 4, and 34 X‐ray structure analyses were performed and are discussed with regard to intramolecular interactions. Preliminary UV/Vis‐spectroscopic results related to π…π interactions in these isoalloxazinophanes are reported.
Aminoglycoside Antibiotics — Modified, Enantiopure Sannamine‐ and Sporamine‐Type Glycosyl Acceptors
Authors: Meier Walter , Seitz Bernhard , Hoenke Christoph , Prinzbach Horst
Published: July 2007

Along an established scheme, 1,2:3,4‐dianhydrodeoxy‐epi‐inositol (3) — readily available from benzene — has been applied to expeditious syntheses of suitably protected, fluorinated, and epimerized aminoglycoside building blocks related to sannamine (rac‐14a, rac‐16a, rac‐18a, rac‐31a) and sporamine (rac‐21a, rac‐23a, rac‐26a, rac‐34a). By separation of diastereomers formed with (+)‐(1‐phenylethyl)amine (14c/ 14′c; 16c/16'c) or with (‐)‐camphanic acid (14e/14'e) and by enzymatic hydrolysis (rac‐14b) access is gained to enantiopure glycosyl acceptors.
Synthese von N‐acylierten 5,10‐Dihydrophenazin‐Verbindungen
Authors: Mikulla Markus , Mülhaupt Rolf
Published: July 2007

Synthesis of N‐Acylated Derivatives of 5,10‐Dihydrophenazine

A family of N‐mono‐ and N, N'‐diacylated 5,10‐dihydrophenazines (4–26) was prepared by reaction of 5, 10‐dihydrophenazine (1) or the corresponding 5,10‐bis(trimethylsilyl) derivative (3) with acyl chlorides. 5,10‐Bis(4‐nitrobenzoyl)‐5,10‐di‐hydrophenazine (11) was hydrogenated to the new aromatic diamine 21 which is an interesting starting material for polymer syntheses.
Das Thermogramm einer C6H6‐Chemie im Temperaturbereich von 450 bis 730°C
Authors: Zimmermann Gerhard , Nüchter Matthias , Remmler Matthias , Findeisen Matthias , Hopf Henning , Ernst Ludger , Mlynek Cornelia
Published: July 2007

Thermal Rearrangements, XXIII[1]. — The Thermogram of a C6H6 Chemistry in the Temperature Range from 450 to 730°C

The thermal isomerization of 1,5‐hexadiyne (1) and its [1,6‐D2]‐labeled derivative (1a) was studied in the temperature range 450–730°C and in the presence of different carrier gases (N2, H2, D2, N2/toluene). By detailed analysis (GC, GC MS, NMR) all volatile reaction products were identified and determined quantitatively by using hexafluorobenzene as an internal standard. The experimental data show clearly that the reaction products are formed by two different routes: (i) electrocyclization leading to dimethylene cyclobutene (3) at temperatures up to about 600°C and (ii) radical reaction leading to benzene (4) and pentafulvene (5) at temperatures above 550°C. Cyclopentadienylmethyl radicals are supposed to be the essential radical intermediates.
Synthesis of 9,10‐Dihydro‐9,10‐propanoanthracene‐12‐ones from Anthracenes and Oxyallyl Cation Intermediates Generated by the the BSA [N,O‐Bis(trimethylsilyl)acetamide] Method
Authors: El‐Wareth Abd , Sarhan A. O. , Martin H. , Hoffmann R.
Published: July 2007

Sonication of a zinc/copper couple, N,O‐bis(trimethylsilyl)‐acetamide (BSA) and α,α'‐oligobromo ketones in benzene gives rise to oxyallyl intermediates which cycloadd to anthracene. Starting from 1,1,3,3‐tetrabromoacetone (2a) and anthracene (1a), we obtained 11,11,13‐tribrominated adduct 4 as the major product (42%). The expected 11,13‐dibrominated adduct trans‐3 was formed as a minor product (5%), but it became the main product when the known oxyallyl methodology was applied. Dibenzohomobarrelenes 9 and 17 were prepared by short routes.
Propargyl‐Stabilisierungsenergie
Authors: Roth Wolfgang R. , Hopf Henning , Horn Carina
Published: July 2007

Propargyl Stabilisation Energy

For the alkynyl‐substituted olefines 1–14 activation parameters for the geometrical isomerisation have been determined in the gasphase by the single‐pulse shoke‐tube technique. By comparison of these barriers with the corresponding one of the isolated double bonds, each corrected by the steric energy contribution of the ground and transition state, a value of 7.8 ± 1.3 kcal · mol−1 for the propargyl stabilisation energy (PrSE) has been derived.
Synthesis of Novel Heteroaromatic Polyfused as‐Triazines by Ring Transformation[1]
Authors: Riedl Zsuzsanna , Hajòs György , Messmer András , Kollenz Gert
Published: July 2007

Ring transformation of the tricyclic furo‐fused as‐triazinium salt 1 in the presence of nucleophilic reagents (e.g. sodium hydrogensulfide, sodium salts of malonic ester, ethyl cyanoacetate, acetylacetone, dimedone, or malononitrile) leads to the two new heteroaromatic ring systems thieno[2,3‐e]pyrido[1,2‐b]‐as‐triazinium salt (5) and differently substituted cyclopenta[e]pyrido[1,2‐b]‐as‐triazine compounds (8, 9, 10, 11, and 13).
Wanzlick‐Carbene in der [4 + 1]‐Cycloaddition mit Bis(methylthio)‐ und Bis(trifluormethyl)‐1,2,4,5‐tetrazin
Authors: Frenzen Gerlinde , Kümmell Andreas , Meyer‐Dulheuer Christiane , Seitz Gunther
Published: July 2007

Wanzlick Carbenes in the [4 + 1] Cycloaddition Reaction with Bis(methylthio)‐ and Bis(trifluoromethyl)‐1,2,4,5‐tetrazine

The 3,6‐disubstituted 1,2,4,5‐tetrazines 3 and 4 have been submitted to a [4 + 1] cycloaddition reaction with the nucleophilic singlet carbenes (Wanzlick carbenes) 2a–d, which are generated from the precursors 1a–d. With 3 as diazadiene the expected spiro compounds 6a–d are formed. In contrast to this presumed two‐step reaction sequence of 3, with the tetrazine 4 the cascade cycloaddition/cycloelimination is surprisingly followed by an intramolecular electrophilic aromatic substitution to yield the chiral tetracyclic compounds of type 8 with high diastereoselectivity. The crystal structure of 8d has been determined by X‐ray diffraction methods.
Ein‐ und zweikernige makrocyclische Übergangsmetallkomplexe mit Liganden vom Schiff‐Basen‐Typ: Synthesen, Strukturen, elektro‐ und magnetochemische Eigenschaften
Authors: Brychcy Klaus , Dräger Klaus , Jens Klaus‐J. , Tilset Mats , Behrens Ulrich
Published: July 2007

Complexes with Macrocyclic Ligands, III[1]. ‐ Mono‐ and Dinuclear Macrocyclic Transition Metal Complexes of Ligands of Schiff Base Type: Syntheses, Structures, Electro‐ and Magnetochemical Properties.

Four new mononuclear metal(II) complexes (4a–d) of a macrocyclic ligand derived from the Schiff base condensation of 2 equiv. of 1,2‐phenylenediamine (3a) and 5‐tert‐butyl‐2‐hydroxy‐1,3‐benzenedicarbaldehyde (2) were synthesized and the cobalt complex 4b characterized by X‐ray structure analysis. Reaction of 1,2‐diamino‐3,4,5,6‐tetrafluorobenzene (3b) with the dicarbaldehyde 2 in the presence of Mn(ClO4)2 or Co(ClO4)2 leads to the novel metal‐free macrocyce 6 (X‐ray structure determination). The macrocycle 6 and Cu(ClO4)2 yield the new dinuclear copper complex 8, the structure of which was also determined by X‐ray diffraction. The copper‐(II) ions in 8 have a distorted square‐pyramidal coordination by the four donor atoms of the macrocycle and an apical acetonitrile ligand. The Cu…Cu distance is 318.1 pm, and the two Cu(II) ions show only a small antiferromagnetic exchange interaction of J= ‐41 cm‐1. Another new dinuclear Cu(II) complex (10) of a macrocyclic ligand derived from the Schiff base condensation of 2,2′‐diaminooctafluorobiphenyl (9) and dicarbaldehyde 2 was synthesized and characterized by X‐ray structure analysis, electrochemical investigations (DCV), and variable‐temperature magnetic susceptibility measurements. One copper ion in complex 10 is five‐coordinate (square‐pyramidal), the other one six‐coordinate (distorted octahedral). The Cu…Cu distance is 301.5 pm and the antiferromagnetic coupling J= ‐774 cm‐1.
Zinkkomplexe von Bis(imidazolylmethyl)sulfiden und ‐oxiden
Authors: Gregorzik Ralf , Vahrenkamp Heinrich
Published: July 2007

Zinc Complexes of Bis(imidazolylmethyl) Sulfides and Oxides

The ligand types bis(benzimidazol‐2‐ylmethyl) sulfide (BIMS), bis(5‐methyl‐4‐imidazolylmethyl) sulfide (MIMS), bis[2‐(benzimidazol‐2‐yl)ethyl] sulfide (BIES), and bis(benzimidazol‐2‐ylmethyl) oxide (BIMO) were used to prepare zinc complexes. With ZnCl2, ZnBr2, and Zn(NO3)2 molecular species L · ZnX2 were obtained in all cases. With Zn(ClO4)2 and Zn(BF4)2 the only isolable species were the ionic complexes [L2Zn]X2. Spectra and the structure determinations of the BIMS · ZnBr2 and MIMS · Zn(NO3)2 complexes have revealed that the thioether sulfur atoms do not coordinate and that all complexes obtained are tetrahedral.
Dimere Bis(trialkylphosphan)rhodiumchloride: Darstellung und Charakterisierung
Authors: Binger Paul , Haas Josef , Glaser Gerald , Goddard Richard , Krüger Carl
Published: July 2007

Dimeric Bis(trialkylphosphane)rhodium Chlorides: Preparation and Characterization

High‐yield methods for the preparation of (PMe3)3RhCl (2) and [(R3P)2RhCl]2 [R = Me (3a); iPr (3b), and cyclohexyl (3c)] are described. The dimeric nature of 3b in the solid state has been established by an X‐ray analysis.
Synthesis and Reactions of 7‐Oxonorbornane‐2,3‐dicarboximides
Authors: Camps Pelayo , Farrés Xavier , Font‐Bardia Mercé , Görbig Diana Marina , Pérez Francesc , Solans Xavier
Published: July 2007

Ozonizations of several 7‐isopropylidenenorbornane‐2,3‐dicarboximides (2, 10) yield 7,7‐dihydroxynorbornane‐2,3‐dicarboximides (3, 11) and/or 7‐oxonorbornane‐2,3‐dicarboxi‐mides (4, 12). Dehydration of the dihydroxy derivatives to the corresponding carbonyl compounds can be carried out by reaction with P2O5 in an aprotic solvent. Reaction of hydrates 3 with methanol gives mixtures of the stereoisomeric hemiacetals 13 and 14, whereas reaction with other nucleophiles give only the stereoisomer derived from attack by the less hindered carbonyl face. Thus NaBH4 or Al(iPRO)3 reduction of 3 or 4 yields alcohols 15 and LiAlH4 reduction of 3 or 4 amino alcohols 16. Reaction of 4b with phenylmagnesium bromide gives alcohol 22 and a direaction product (rac‐26) that easily dehydrates to a tetracyclic compound (rac‐30). Reductive aminations of 3 or 4 lead to amines 19 directly or via imines rac‐20 and amines 23. LiAIH4 reduction of amine 23b affords tricyclic compounds (rac‐27) and (rac‐28). The last one was converted to diamine 24 by reduction with NaBH3CN. Similarly, amine 21 was converted into diamine 25, partially via aminal 29 as intermediate. The structures of compounds 3b, 19a, rac‐27, and rac‐30 have been established by X‐ray diffraction analysis.
Neue Synthesen von Methyleniminium‐Salzen aus Carbonylverbindungen und aus α‐Chlorethern; ein Zugang zu vinylogen Viehe‐Salzen*
Authors: Schroth Werner , Jahn Ullrich , Ströhl Dieter
Published: July 2007

New Syntheses of Methyleniminium Salts from Carbonyl Compounds and from α‐Chloro Ethers; an Access to Vinylogous Viehe Salts*

Two methods for the synthesis of isolable methyleniminium salts and amidinium salts are presented. In the first case carbonyl compoundsAare treated with a mixture of (dialkyl‐amino)trimethylsilane (12) and chlorotrimethylsilane (13) or12and trimethylsilyl triflate (14) leading to the iminium chloridesFor iminium triflatesG, respectively. With12/13the preparation ofFis limited to non‐enolizable aldehydes and dimethylformamide (10), while12/14enables the preparation ofG, e.g.23a–25a, 27a, also with ketones and with substituted amides. The second procedure is based on the treatment of α‐chloro ethersLwith12. Both methods afford the Mannich reagent16ain high yields. By reaction of the α‐chloro ether35with12in diethyl ether the vinylogous Viehe salts36a–c, ebecome available for the first time. The reaction pathways are discussed.
X‐Ray Crystal Structures of the Enolate of tert‐Butyl α‐Cyanoacetate with Li+ or Protonated 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU‐H+) as Gegenion. N—H Hydrogen Bridge from DBU‐H+ to the Enolate Oxygen Atom
Authors: Boche Gernot , Langlotz Ira , Marsch Michael , Harms Klaus
Published: July 2007

For the first time a solid‐state structure with protonated 1,8‐diazobicyclo[5.4.0]undec‐7‐ene (DBU‐H+) as the gegenion of an “organic” anion, namely tert‐butyl α‐cyanoacetate (2‐), is determined. The DBU‐H+ N—H bond forms a hydrogen bridge to the enolate oxygen atom of 2‐, the first N‐H bridge to an enolate oxygen atom ever characterized. The structure of 2‐ DBU‐H+ is compared with that of the corresponding lithium compound [2‐ Li+ · TMEDA]2 in which the cations are bound to the N atoms of the cyano groups and the enolate O atoms forming a twelve‐membered ring. Literature reports on the rather different chemistry of anions like 2‐ having alkali metal ions or DBU‐H+, respectively, as the gegenions can be understood by means of the two new solid‐state structures disclosed in this publication.
Electronic Structure and Gas‐Phase Thermolysis of 2‐Tetrazenes with Acyclic or Cyclic Amino Groups Studied by Photoelectron Spectroscopy
Authors: Rademacher Paul , Heymanns Peter , Münzenberg Ralf , Wöll Heike , Kowski Klaus , Poppek Rainer
Published: July 2007

The electronic structures and the gas‐phase thermolyses of the 2‐tetrazenes 2–13 have been studied by He(I) photoelectron spectroscopy. The compounds are characterized by at least three ionization potentials with energies less than 10 eV which are assigned to the molecular orbitals π3 (HOMO), n+, π2, and n‐. In the thermolyses either the formal disproportionation products (amine and imine) of the respective aminyl radical are found, or the latter is stabilized by loss of an alkyl radical affording also an imine. Further products which can be explained by radical reactions are detected in flash vacuum pyrolyses. The tricyclic cis‐2‐tetrazene 13 is cleaved by [2 + 2 + 2] cycloreversion. The methoxymethylsubstituted compound 8 exhibits a more complex cleavage pattern.
Novel dinuclear palladium(II) complexes with the chelating ligand bis(1‐methylimidazol‐2‐yl) ketone (bmik) and pyridine‐2‐thiolate, pyrimidine‐2‐thiolate, and 1‐methylimidazole‐2‐thiolate as bridging secondary ligands
Authors: Engelking Holger , Karentzopoulos Stefan , Reusmann Gerhard , Krebs Bernt
Published: July 2007

Three novel dinuclear palladium(II) complexes with the chelating ligand bis(1‐methylimidazol‐2‐yl) ketone (bmik) as well as pyridine‐2‐thiolate (pyt), pyrimidine‐2‐thiolate (pymt), and 1‐methylimidazole‐2‐thiolate (meimt) as bridging secondary ligands were prepared by reactions of diaqua[bis(1‐methylimidazol‐2‐yl) ketone]palladium(II) nitrate with the ligands in aqueous solution. The thiolates bridge the two metal atoms in the μ‐N,S mode. The structures of the following compounds were analyzed by single crystal X‐ray diffraction: Bis(μ‐pyridine‐2‐thiolato‐N,S)‐bis{[bis(1‐methyl‐imidazol‐2‐yl) ketone]palladium(II)}nitrate [Pd2(bmik)2‐(pyt)2](NO3)2 · 5 H2O (1), bis(μ‐pyrimidine‐2‐thiolato‐N1,S)‐ bis{[bis(1‐methylimidazol‐2‐yl) ketone]palladium(II)} nitrate [Pd2(bmik)2(pymt)2](NO3)2 · 5 H2O (2), and bis(μ‐1‐methyl‐imidazole‐2‐thiolato‐N3,S)‐bis{[bis(1‐methylimidazol‐2‐yl) ketone]palladium(II)} nitrate [Pd2(bmik)2(meimt)2](NO3)2 · 4.5 H2O (3). In the cases of 1 and 3 the bridging thiolate ligands show head‐to‐head orientation. For complex 2 a head‐to‐tail orientation of the pyrimidine‐2‐thiolates was found. The metal‐metal distances vary from 2.963 Å in complex 3 and 2.915 Å in 1 to the shortest of 2.886 Á in 2. In addition to the X‐ray crystallography the three compounds were characterized by 1H‐NMR and IR spectroscopy.
1,3‐Diaza‐2λ2‐phosphonia‐4λ4‐gallatacyclobutane
Authors: Oberdörfer Richard , Nieger Martin , Niecke Edgar
Published: July 2007

1,3‐Diaza‐2λ2‐phosphonia‐4λ4‐gallatacyclobutanes

Reaction of amino(imino)phosphanes 1a‐c with gallium trichloride results in the formation of 1,3‐diaza‐2λ2‐phosphonia‐4λ4‐gallatacyclobutanes 3a, b with elimination of chlorotrimethylsilane (1a) or tert‐butyl chloride (1b, c). The intermediately formed amino(imino)phosphane/Lewis acid adducts R(Me3Si)NPN(GaCl3)R′ (2, R,R′ = tBu, Me3Si) can be isolated in the case of compound 2a (R = R′ = SiMe3). A diazaphosphasilacyclobutane ‐ gallium trichloride adduct 4 is formed in a side reaction by isomerization of 2a. Reaction of compound 3b with Ni(CO)4 gives the corresponding transition metal complex 5. The NMR data and X‐ray structures of compounds 2a, 4, and 5 are reported.
Propellane, 10[1] Bis‐ und Tris(propellane) aus Methylbenzolen: 1,2;3,4;5,6‐Tris{8′,11′‐dioxa[4.3.3]propella(3′,4′)}benzol
Authors: Jamrozik Janusz , Żeslawski Wojciech
Published: July 2007

Propellanes, 10[1]. ‐ Bis‐ and Tris(propellanes) from Methylbenzenes: 1,2;3,4;5,6‐Tris{8′,11′‐dioxa[4.3.3]propella(3′,4′)}benzene

The synthesis of the title tris(propellane) 17, derived from hexamethylbenzene, and bis(propellane) 12 is reported. Some aspects of the conformation of the compounds 12 and 17 are studied by 1H‐NMR spectroscopy. Compound 17 exists as an equilibrium of two conformers with C3 and C1 symmetry. In the case of propellane 10, the formation of an isomeric bispirane compound is discussed.
Reactivity Tuning by Ligand Effects: Gas‐Phase Reactions of Fe(C6H6)O+ versus “Bare” FeO+
Authors: Stöckigt Detlef , Schwarz Helmut
Published: July 2007

The presence of a benzene ligand in Fe(C6H6)O+ (1) has a profound effect on the gas‐phase reactivity of FeO+. While the latter oxide is known to act as an efficient C‐H/C‐C bond‐activation reagent, the ligated species 1 is entirely unreactive in that respect. However, 1 serves as an excellent reagent for transferring oxygen to various olefins. In addition, it is demonstrated that the ligand substitution Fe‐(C6H6)O+ + X → Fe(X)O+ + 6H6) follows two principally different pathways. For X = C6D6 and C5H5N the traditional direct substitution process with attack at the metal centre is operative. However, for X = olefins it is argued that the olefin will not initially attack the metal center; rather, the reaction commences by coordinating the olefin X to the oxygen atom of Fe6H6)O+. The resulting intermediate (6H6)Fe(OX)+ will then fall apart either to separated Fe(OX)+/6H6) or to Fe(6H6)+/OX, thus bringing about an epoxidation of the olefin rather than ketone formation.
Stereoselective Synthesis of Alcohols, XLVIII[1] Linear Synthesis of (9S)‐Dihydro‐Erythronolide A
Authors: Stürmer Rainer , Hoffmann Reinhard W.
Published: July 2007

Starting from building block 3 comprising the C‐7 to C‐15 segment of erythronolide A, a linear synthesis of erythronolide A has been achieved. Key steps were a Sharpless‐epoxidation to set up the sterocenter at C‐6, and two stereoselective allylboration reactions to generate the stereocenters at C‐2, C‐3, C‐4, and C‐5.
Two Alternatives of Heteroallene Insertion in Metal — Ligand Bonds of Five‐Coordinate Ruthenium(II) and Osmium(II) Complexes [MXY(CO)(PiPr3)2]
Authors: Werner Helmut , Tena Miguel Angel , Mahr Norbert , Peters Karl , Schnering Hans‐Georg Von
Published: July 2007

The five‐coordinate chloro(hydrido)‐ and hydrido(iodo)ruthenium(II) and ‐osmium(II) compounds [MHX(CO)(PiPr3)2] (1, 2, 6, 7) react with CS2 to give the octahedral dithioformato complexes [MCl(CO)(PiPr3)2(η2‐S2CH)] (3, 4, 8, 9) in excellent yields. In the initial step, an addition of the heteroallene to the metal center occurs which is followed by insertion of CS2 into the M—H bond. On treatment of the dichlororuthenium(II) derivative [RuCl2(CO)(PiPr3)2] (10), which is prepared from RuCl3 · aq and PiPr3 in methanol, with carbon disulfide insertion into one of the Ru—PiPr3 bonds takes place to give the six‐coordinate ruthenium(II) complex 12 with zwitterion −S2CPiPr3+ as a chelating ligand. While the reaction of [OsH(SPh)(CO)(PiPr3)2] (13) with MeSCN leads to addition of the thionitrile to the metal center, the starting material reacts with MeNCS by insertion of the heteroallene into the Os—SPh bond to give two stereoisomers 15a, b, in which the nitrogen atom of the chelate ring is either cis or trans to the hydrido ligand. The octahedral methoxydithiocarbonato‐ and formatoosmium(II) compounds 16 and 17 are prepared from 2 and CS2 or CO2 in the presence of NaOMe. The crystal and molecular structures of 4 (M = Os), 12 and 15a have been determined.
Die ersten Organobor‐Tellur‐Verbindungen[1]
Authors: Köuster Roland , Seidel Güunter , Schüuβler Wilhelm , Wrackmeyer Bernd
Published: July 2007

Na2Te and Na2Te2, prepared from Te and Na[Et3BH], react with 9‐Cl‐9‐BBN to form bis(1,5‐cyclooctanediylboryl) telluride (1) and bis(1,5‐cyclooctandiylboryl) ditelluride (2), resp. 1 reacts with water to give elemental Te, (9‐BBN)2O, and (9H‐9‐BBN)2.
Trimeric Iridium(I) and Iridium(III) Complexes with the Tripodal Phosphane cis, cis‐1,3,5‐Tris[(diphenylphosphanyl)methyl]cyclohexane (tdppmcy) as Bridging Ligand
Authors: Mayer Hermann A. , Kaska William C.
Published: July 2007

Treatment of cis,cis‐1,3,5‐tris[(diphenylphosphanyl)methyl]‐cyclohexane (tdppmcy) (1) with Ir(PPh3)2(CO)Cl in toluene gives the trinuclear complex [Ir(CO)Cl]3(tdppmcy)2 (2) in high yield. In this complex the tripodal molecule tdppmcy behaves as a trismonodentate ligand since each phosphorus atom is bound to one metal center. Compound 2 can be transformed into the trinuclear complexes {[Ir(CO)‐(Cl)H]3(tdppmcy)2)3+ (3), [Ir(CO)(Cl)H2]3(tdppmcy)2 (4), and [Ir(CO)H3]3(tdppmcy)2 (5) by treatment with H+, H2, and H−, respectively. The chemistry of 2 supports the spectroscopic findings of a square‐planar environment at the metal centers in 2.
Protolysis of Tri‐tert‐butylazadiboriridine: Formation of a B‐H‐B Bridge in Unusual Coordination
Authors: Müller Matthias , Eversheim Ellen , Englert Ulli , Boese Roland , Paetzold Peter
Published: July 2007

The BB bond of tri‐tert‐butylazadiboriridine [NRBRBR] (R = tBu; 1) is oxidized by MeOH to give the (hydroboryl)(methoxyboryl)amine HBRNR‐BR(OMe) (2a). μ‐2,3‐Hydroazoniadiborata‐1‐cyclopropenes [NRBR(X)μHBR] (3a, 3c‐e) are formed by the action of the acids HX upon 1. A similar hydrogen bridge as in 3a‐e is formed during the hydroboration of 1 by catecholborane, yielding 3f. A B atom is identified in the products 3a‐f to be planarly coordinated by four atoms, two of which are forming a BHB three‐center bond with that B atom. This is a novel bonding situation in boron chemistry. The structures of the products are deduced from 1H‐, 11B‐, and 13C‐NMR spectra and are confirmed by X‐ray structural analyses of 2a, 3a, and 3c.