bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ein ungewöhnliches Paar Bis(phosphido)‐verbrückter Dieisencarbonylkomplexe: [Fe2(CO)n{μ‐P(tBu)2}(μ‐PCy2)] (n = 5 und 6)
Authors: Waltherη Bernhard , Hartungη Helmut , Böttcher Hans‐Christian , Baumeister Ute , Krug André , Reinholdη Zzjoachim , Jones Zzpeter G. 
Published: July 2007

An Unusual Pair of Bis(phosphido)‐Bridged Diiron Carbonyl Complexes: [Fe2(CO)n{μ‐P(tBu)2}(μ‐PCy2)] (n = 5 and 6)Treatment of Na[Fe2(CO)6(μ‐CO){μ‐P(tBu)2}] with Cy2PCl gives [Fe2(CO)6{μ‐P(tBu)2}(μ‐PCy2)] (1) which loses CO on heating in toluene to afford [Fe2(CO)5{μ‐P(tBu)2}(μ‐PCy2)] (2). Complexes 1 and 2 have been characterized spectroscopically and by X‐ray analyses. The central Fe2P2 unit in 1 is exactly planar whereas in 2 it is somewhat folded.
Synthesewege zu neuen ionischen Ozoniden
Authors: Korber Nikolaus , Jansen Martin 
Published: July 2007

Synthetic Routes to New Ionic OzonidesNew synthetic routes to tetraorganylammonium ozonides involving exchange reactions with alkali metal ozonides were investigated. The previously reported reaction between tetraalkylammonium hyperoxides R4N+O2‐ (R = Me, Et) and alkali metal ozonides in liquid ammonia is severely hampered by the difficult synthesis of these hyperoxides; they are unknown for other quaternary ammonium cations. A similar reaction between the easily accessible chlorides of trialkylbenzylammonium ions and KO3 yields mixed ozonides/chlorides due to some solubility of KCl in liquid ammonia. The new compounds BzlMe3N+ (O3‐)0.6Cl‐0.4 (3), BzlEt3N+ (O3‐)0.8Cl0.2‐ (4) and Bzl(nBu)3N+(O3‐)0.5Cl0.5‐ (5) were prepared by this route. – The by far superior route to new ozonides utilizes macroreticular cation exchange resins in liquid ammonia. Batch equilibration between an excess of the appropriate ionic form of the resin and CsO3 produced Me3PhN+O3‐ (6), BzlMe3N+O3‐ (7), Bzl(nBu)3N+O3‐ (8), and (nPr)4N+ O3‐ (9) in almost quantitative yield. Compounds 4, 6, and 7 were studied by single‐crystal X‐ray analysis; the shortening of the ozonide bond length and the widening of the bond angle in comparison to the alkali metal ozonides as well as the possibility of C–H…O hydrogen bonding are discussed. Thermal stabilities were determined by DTA/TG methods, rapid decomposition starts at 59–79°C for 3, 6, and 7 and at 28–56°C for the remaining new ozonides which contain detachable β‐H atoms.
First evidence of unhindered silanimines obtained by flash vacuum thermolysis and vacuum gas‐solid reaction
Authors: Denis Jean‐Marc , Pellerin Zzbruno , Guenot Pierre , Letulle Marguerite , Ripoll Jean‐Louis 
Published: July 2007

AbstractThe unhindered silanimines 1,1‐dimethyl‐N‐phenylsilanimine (2) and N‐isopropyl‐1,1‐dimethylsilanimine (10) have been generated by flash vacuum thermolysis of the N‐allylsilanamine 1 and vacuum gas‐solid reaction of the 1‐chlorosilanamine 9, respectively. The silanimines 2 and 10 have been characterized by MS as well as by chemical trapping to yield 3 or dimerization to the cyclodisilazane 11.
Ein Zirconiumamid‐Komplex mit Si‐β‐H–Zr‐Wechselwirkungen
Authors: Herrmann Wolfgang A. , Huber Norbert W. , Behm Joachim 
Published: July 2007

A Zirconium Amide Complex with Si‐β‐H–Zr InteractionsZrCl4 (1) reacts in diethyl ether with Li[N(SiHMe2)2] (2) to form the title compound of formula [ZrCl(μ‐Cl){N(SiHMe2)2}2]2 (3). A single‐crystal X‐ray structure analysis in combination with IR data provides evidence for an unprecedented type of β‐hydrogen interactions between a silicon‐attached hydrogen atom of the bis(dimethylsilyl)amide ligand and the zirconium atom (Zr–N–Si–H).
Elektroreduktion organischer Verbindungen, 20[ Darstellung von Bicyclo[n.1.0]alkanen durch elektrochemische Reduktion von 1,3‐Dibromcycloalkanen
Authors: Hoffmann Joachim , Voß Jürgen 
Published: July 2007

Preparation of Bicyclo[n.1.0]alkanes by Electrochemical Reduction of 1,3‐DibromocycloalkanesGood yields of bicyclo[2.1.0]pentane (17) and bicyclo[3.1.0]‐hexane (3) are obtained on electroreduction of the corresponding 1,3‐dibromocycloalkanes. The results do not depend upon the stereochemistry of the starting material (14 vs. 15 or 11 vs. 12).
Asymmetric induction in reductively initiated [2,3]‐Wittig and retro [1,4]‐brook rearrangements of secondary carbanions
Authors: Hoffmann Rolf , Brückner Reinhard 
Published: July 2007

AbstractThe synthesis of O,S‐acetals and the lithium naphthalenide initiated rearrangement reactions thereof are described. O,S‐Acetal 8a resulted from trapping of the 1,4‐dipole 7 with thiophenol. O,S‐Acetals 16a and b were obtained from aldehydes 14a/b by a one‐pot reaction with (trimethylsilyl)prenol, (tri‐methylsilyl)thiophenol, and trimethylsilyl triflate. Upon reduction with lithium naphthalenide all O,S‐acetals delivered α‐lithiated ethers. They rearranged either in a [2,3]‐Wittig mode furnishing the 1,3‐diol derivatives 20a–h/21 with moderate stereoselectivity (syn:anti = 35:65 to 78:22) or underwent retro [1,4]‐Brook rearrangements yielding the α‐silyl ethers 23i–k/24 with still less stereocontrol (syn:anti = 34:66 to 50:50). The mechanistic implications are discussed.
Neue Wege zum Aufbau von Te–N‐Bindungen – Synthese, Struktur und Eigenschaften von Cl6Te2N2S
Authors: Haas Alois , Kasprowski Jörg , Pryka Michael 
Published: July 2007

New Routes for the Formation of Te–N Bonds – Synthesis, Structure, and Properties of Cl6Te2N2SBesides Cl2magnified image (1), the reaction of Se(NSO)2 with TeCl4 leads to the formation of [Se2N2S]22+[TeCl5‐]2 (2) and the bicyclic heterocycle Cl6Te2N2S (3). The latter is also accessible by treating Se(NSO)2 with TeCl3+AsF6‐. Another product of this reaction is the well‐known salt [Se2N2S]22+[AsF6‐] 2. Treatment of TeCl4 with Me3SiNSO in CH2Cl2 provides 3 on a preparative scale. Its structure has been determined by X‐ray crystallography.
Übergangsmetall‐substituierte Diphosphene, XXVII[1] Synthese und Struktur des Diphosphirans (η5‐C5Me5)(CO)2Fe–H[Cr(CO)5]
Authors: Weber Lothar , Kirchhoff Ralf , Stammler Hans‐Georg , Neumann Beate 
Published: July 2007

Transition‐Metal‐Substituted Diphosphenes, XXVII[1]. – Synthesis and Structure of the Diphosphirane (η5‐C5Me5)(CO)2Fe–Pmagnified imageH[Cr(CO)5(η5‐C5Me5)(CO)2FePH2 (5), prepared from (η5‐C5Me5)(CO)2Fe‐P(SiMe3)2 and ethanol, reacts with one equivalent of ClP = C(SiMe3)2 to give the diphosphirane (η5‐C5Me5)(CO)2Femagnified imagePH (8). Compound 8 is converted into the iron chromium complex [(η5‐C5Me5)(CO)2Fe–magnified imageH]Cr(CO)5(9). In contrast, the reaction of 5 with two equivalents of ClP=C(SiMe3)2 results in the formation of the cyclotri‐phosphane [(η5‐C5Me5)(CO)2Fe–magnified image[CH(SiMe3)2] (12). The molecular structure of 9 is elucidated by single‐crystal X‐ray analysis.
Formal coupling of two alkylidyne ligands on a metal center
Authors: Mayr Andreas , Bastos Cecilia M. , Daubenspeck Nancy , McDermott Gregory A. 
Published: July 2007

AbstractReaction of the alkylidyne complexes [W(CR)Br(CO)3L] [2b (L = CO; R = C6H4‐OMe‐4), 2c (L = CO, R = C6H4‐NMe2‐4), 3a (L = PPh3; R = Ph), and 3c (L = PPh3; R = C6H4‐NMe2‐4)] with methyllithium in THF at ‐78°C affords the alkylidyne acyl tungsten complexes Li[W(CR)(COMe)Br(CO)3L] [4b (L = CO; R = C6H4‐OMe‐4), 4c (L = CO, R = C6H4‐NMe2‐4), 5a (L = PPh3; R = Ph), and 5c (L = PPh3; R = C6H4‐NMe2‐4)]. Reaction of complexes 4 and 5 with C2O2Br2 at ‐78°C‐0°C in CH2Cl2 followed by addition of PPh3 gives the alkyne complexes [WBr2(CO)(CH3C = CR)(PPh3)2] (6). The formation of the alkyne ligands in complexes 6 may be considered as the result of formal coupling of two alkylidyne ligands.
Enol cation radicals in solution, 3[1] Reaction of enol cation radicals in the presence of nucleophiles
Authors: Schmittel Michael , Röck Maik 
Published: July 2007

AbstractThe one‐electron oxidation chemistry of three diaryl‐substituted enols, 1,1‐dimesityl‐1‐propen‐2‐ol (7), 1,2‐dimesityl‐1‐propen‐1‐ol (8), and 2‐mesityl‐2‐phenylethenol (9), has been examined. As a consequence of the pronounced steric shielding around the β‐carbon, 7 does not react with nucleophiles upon addition of 2 eq. of oxidant, but cyclizes to yield benzofuran 18. Under identical conditions, the less shielded enols 8 and 9 react with methanol and other nucleophiles. Several mechanistic hypotheses for nucleophile incorporation are tested, thus allowing the second part of the α‐umpolung reaction of ketones via enol cation radicals to be elucidated mechanistically. Fast‐scan cyclic voltammetry studies (2000 V · s‐1) show no reversible wave of the enol cation radicals. The corresponding methyl enol ether cation radicals, however, have a lifetime of several seconds at ‐10°C, and the kinetics of their reactions with acetonitrile and methanol was probed. The results obtained are consistent with fast deprotonation being the primary reaction of enol cation radicals. Under the given oxidative conditions the radicals formed are further oxidized. Consequently one‐electron oxidation of enols provides an interesting entry to α‐carbonyl carbocation chemistry.
Folgereaktionen von Sulfenen aus Sulfonylchloriden und tertiären Aminen, 3[1,2] Kristallstrukturanalyse von Bis(trimethylammoniosulfonyl)methanid‐tetraphenylborat. – n‐σ*‐Wechselwirkungen (Hyperkonjugation und Homohyperkonjugation) in Sulfen–Amin‐S,N‐Addukten
Authors: Opitz Günter , Wiehn Walter , Ziegler† Manfred L. , Nuber Bernhard 
Published: July 2007

Secondary Reactions of Sulfenes from Sulfonyl Chlorides and Tertiary Amines, 3[1,2]. – Crystal Structure Analysis of Bis(trimethylammoniosulfonyl)methanide Tetraphenylborate. – n‐σ*‐Interactions (Hyperconjugation and Homohyperconjugation) in Sulfene – Amine S,N‐AdductsBis(trimethylammoniosulfonyl)methanide chloride (3b) could be obtained in 97% yield by reaction of methanedisulfonyl dichloride (5) with three equivalents of trimethylamine. X‐ray analysis of the tetraphenylborate 3c reveals that the conformation of the cation is determined by nC‐σ*S–N interactions (negative hyperconjugation) and by nC‐σ*N–C interactions (negative homohyperconjugation). These effects were deduced from alterations of the bond lengths within the S–N–C chains which are coplanar to the occupied pz orbital at the central C atom. Comparison with known crystal structure data shows, that sulfene – amine S,N‐adducts generally have the zwitterionic ammoniosulfonylmethanide structure 3, stabilized by nC‐σ* interactions.
Organische Synthesen mit Übergangsmetall‐Komplexen, 59[1] Cyclobutanimine aus Carbenchrom‐ oder ‐wolfram‐Komplexen, Isocyaniden und Alkenen durch [2 + 2]‐Cycloadditionen intermediärer Ketenimin‐Komplexe; Liganden‐Abspaltung mit Pyridin
Authors: Aumann Rudolf , Krüger Carl , Goddard Richard 
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 59[1]. – Cyclobutanimines from Carbenechromium or ‐tungsten Complexes, Isocyanides, and Alkenes by [2 + 2]‐Cycloaddition Reactions of Ketenimine Complexes; Ligand Disengagement with Pyridine10‐Iminotricyclo[5.3.0.02,9]deca‐3,5‐diene complexes syn/anti‐4 are obtained in yields higher than 90% by the addition of isocyanides RNC 2 [R = c‐C6H11 (a), CH3 (b)] to (cycloheptatrien‐1‐ylmethyl)carbene complexes LnM=C(OEt)CH2(C7H7) 1 [LnM = Cr(CO)5 (a), W(CO)5 (b)]. The reactions involve an intermediate formation of ketenimine complexes LnM[RN=C=C(OEt)CH2C7H7] 3 by the insertion of 2 into the M=C bonds of 1. Complexes 3 isomerize to give the cyclo‐butanimines 4 by an intramolecular [2s + 2a]‐cycloaddition reaction of the ketenimine to the alkene unit. The structure of anti‐4c has been determined by a crystal structure analysis. Complexes 4 react with pyridine by the fragmentation of the four‐membered ring to yield a tetrahydroazulen‐1‐imine 6 which was hydrolyzed to the corresponding ketone 7;7 is also obtained along an independent route by the photolysis of 1a in the presence of carbon monoxide. The first isolated product of the latter reaction is the tricyclo[5.3.0.02,9]deca‐3,5‐dienone 9, which presumably is formed via an intermediate ketene complex N and the tricyclic ketone O; 9 on warming with pyridine rearranges to 7.
Nitrile Addition to (η4‐Butadiene)zirconocene: The Formation of Organometallic and Metal‐Free Hexatrienediamine Derivatives
Authors: Erker Gerhard , Pfaff Ronald , Krüger Carl , Nolte Matthias , Goddard Richard 
Published: July 2007

Abstract(η4‐Butadiene)zirconocene adds one equivalent of benzonitrile to form the five‐membered azazirconacyclopentene derivative 7, which contains an NH group in the ring and a vinyl substituent at the α‐carbon center. The reaction of 7 with an additional equivalent of benzonitrile furnishes the chiral nine‐membered metallacycle (magnified image) (12) which may be isomerized to the thermo‐dynamically favored tautomer (magnified image) (13). The Gibbs activation energy of the enantiomerization of the trans‐cycloalkene‐like 13 is ΔG#(323 K) = 15.5 ± 0.3 kcal mol‐1. The analogous conformational equilibration of 12 has a lower activation barrier of ΔG# (236 K) = 12.1 ± 0.3 kcal mol‐1; complex 13 is characterized by X‐ray diffraction. Hydrolysis of 13 yields the conjugated 1,6‐diamino‐1,6‐diphenylhexatriene 16 which is characterized by X‐ray diffraction.
The Pagodane Route to Dodecahedranes Directed Conversions – The Pagodane → Bissecododecahedradiene Stage
Authors: Fessner Wolf‐Dieter , Murty Bulusu A. R. C. , Spurr Paul R. , Pinkos Rolf , Melder Johann‐Peter , Fritz Hans , Prinzbach Horst 
Published: July 2007

AbstractThree conceptual routes (A, B, C) from [1.1.1.1]pagodane (1) to pentagonal dodecahedrane (2) are evaluated by MM2 (MM3) calculations. After limited experimental success with a catalytic one‐pot route (A), a more selective transformation along one of two stepwise routes (B/C) is explored. An expeditious entry into route C is achieved by hydrogenolytic cyclobutane opening in 1; secopagodane 7 (100%), however, resists both progression along route C (dehydrogenative C—C bond formation to isododecahedrane 8) and crossover into route B (hydrogenolysis to bissecododecahedrane 5). The first transformation along route B, the 2sigma;→2π‐isomerization of the highly strained 1 to bissedodecahedra‐1,10(11)‐diene 3, is not attainable by metal catalysis and cannot productively be brought about by thermal activation: The necessarily very high reaction temperatures (> 700°C) enforce instead a mechanistically interesting fragmentation into two C10H10 halves to give ultimately naphthalene. The very rapid pagodane opening occurring after one‐electron oxidation, too, is not a preparatively useful alternative. Highly efficient, on the other hand, is a two‐step process affording a high yield of the product and consisting of regiospecific, photochemically induced bromine addition to the central four‐membered ring (→ dibromosecopagodane 37) followed by reductive bromine elimination (→ diene 3). In spite of the necessarily rather severe reaction conditions in both steps, this procedure is applicable to the preparation of various 3,8‐difunctionalized bissecodienes (dienedione 11, diene diesters 43, 50, 52, dichlorodiene 56). Limitations of this procedure are met with the 4,4,9,9‐tetrachloropagodane 60 (inert) and the [2.2.1.1]pagodane 80 (bridgehead bromination). The lateral half‐cages of the (seco)‐pagodane structures are explored for preparatively (dis)advantageous steric effects, that might be later exploited on the way towards functionalized dodecahedrane derivatives.
Reaktionen koordinierter Liganden, XVIII. Templatsynthesen und Peripheriereaktionen makrocyclischer Multiphosphanliganden mit funktionellen Gruppen
Authors: Brauer David J. , Dörrenbach Frank , Lebbe Thomas , Stelzer Othmar 
Published: July 2007

Reactions of Coordinated Ligands, XVIII. – Template Syntheses and Periphery Reactions of Macrocyclic Multiphosphane Ligands with Functional GroupsCyclisation of the tridentate phosphanes PhP([CH2]3PRH)2 (R = H, Me) with the divinyl components R′P(CHCH2)2 [R′ = Ph, NEt2, O(iPr)] within Ni(II) templates affords complexes NiBr2L (3a–f) of functionalised macrocyclic tetraphosphanes (L) in almost quantitative yields. An X‐ray structural analysis of the cyano complex [Ni(CN)L]PF6 (5a), obtained by metathetical reactions, reveals a folded 14‐membered macrocyclic ligand L. The P atoms occupy axial and equatorial positions within the trigonal‐bipyramidal ligand arrangement with an equatorial CN group. By periphery reactions at the P–NEt2 function of the 14‐membered ring system POH, PO−, PCl, POR″ derivatives (R″ = Me, iPr, CH2CHCH2) are formed. Addition of methyl acrylate to the PH functions in 3d and 3f leads to macrocyclic diesters 12a, 12b. By cleavage of the PN bond in 3a with concentrated aqueous HBr a complex of composition 7a · HBr · 3 H2O is obtained. An X‐ray structural analysis of the latter shows a POH functionalised macrocyclic tetraphosphane occupying the four basal positions within a square pyramidal coordination geometry at Ni(II).
Derivate des Borols, XVIII. Tricarbonyl[η5‐(1‐phenylborol)]eisen: Zur Reaktivität der koordinierten Liganden
Authors: Herberich Gerhard E. , Carstensen Tobias , Klaff Norbert , Neuschütz Mark 
Published: July 2007

Derivatives of Borole, XVIII. – Tricarbonyl[η5‐(1‐phenylborole)]iron: Reactivity of the Coordinated LigandsThe borole complex (C4H4BPh)Fe(CO)3 (1) undergoes Friedel‐Crafts acetylation (MeCOCl/AlCl3) at the meta‐position of the phenyl substituent while the derivatives (C4H4BPh)Fe(CO)2L (3, a: L = NMe3′ b: L = PMe3) are acetylated at the 2‐position of the borole ring. Organolithium reagents (LiMe, LiBu) add to 1 at the boron atom below – 50°C while nucleophilic attack at the carbonyl C atom takes place at higher temperature with formation of acyl anions [(C4H4BPh)Fe(CO)2(COR)]− (6a,b−). The Fischer carbene complex (C4H4BPh)Fe(CO)2[C(OMe)Me] (7) is obtained from 6a−/[Me3O]BF4. Complex 1 reacts with LiN(SiMe3)2 to give [(C4H4BPh)Fe(CO)2(CN)]− (8−) and with 5 M NaOH/C6H6/NBu4HSO4 to produce the hydride NBu4‐[(C4H4BPh)FeH(CO)2] (NBu4 · 9). A highly reactive dianion [(C4H4BPh)Fe(CO)2]2− (102−) is obtained by deprotonation of 9− or by reduction of 1 or 3a in THF at −70°C. Treatment of 102− with Ph3SnCl gives [(C4H4BPh)Fe(CO)2(SnPh3)]− (11−) which is isolated as NEt4 · 11. Slow reduction of 3a with sodium amalgam in THF at −30°C produces doubly CO‐bridged cis‐[{(C4H4BPh)Fe(CO)2}2]2− (122−) which is protonated to the μ2‐hydrido anion [μ‐H‐{(C4H4BPh)Fe(CO)2}2]− (13−).
Amidoxim‐Nachbargruppen in Cyclodehydrierungsreaktionen
Authors: Möhrle Hans , Lessel Jürgen 
Published: July 2007

Amide Oxime Functions as Neighbouring Groups in Cyclodehydrogenation ReactionsDehydrogenation of the o‐(tertiary amino)benzamide oximes 4, which are monosubstituted at the amide N atom of the neighbouring group, by the mercury edta complex yields tricyclic amino nitrones 9 with a quinazoline 3‐oxide moiety or lactams 8. Product formation depends on the nature of the N substituent, the size of the amine ring, and the reaction conditions. The configuration of the amide oximes and the conformation of the tricyclic systems is determined by NMR‐spectroscopic methods.
Regiochemistry of the Intramolecular [2 + 2] Photocycloaddition of Enones to Vinyl Ethers as a Function of Chain Length
Authors: Gleiter Rolf , Fischer Evelyn 
Published: July 2007

AbstractThe intramolecular [2 + 2] cycloaddition of a cyclohexenone moiety bound to a vinyl ether fragment has been explored. The regiochemistry and the quantum yield of the reaction have been investigated as a function of the chain length n and the position of the methoxy group. It has been found that in those cases where the chain consists of three and four members the position of the methoxy group has no influence on the regiochemistry but on the quantum yield. Only head‐to‐head cycloaddition is observed. In the case of n = 2 both the regiochemistry and the quantum yield depend strongly on the position of the methoxy group. It is concluded that the main reason for the different behavior of n = 2 is due to a through‐bond effect between the two olefinic units mediated by a C2H4 bridge.
Imidazole Derivatives, VII. Reaction of 1‐Acylimidazoles with Dialkyl Acetylenedicarboxylates: Synthesis of Imidazo[1,2‐a]pyridines, (2‐Imidazolyl)maleates, 1,5‐Dihydroimidazo[1,2‐a]pyridines, Furo[2′,3′: 2,3]pyrrolo[1,2‐a]imidazoles, Furo[2′,3′: 2,3]pyrrolo[1,2‐a]benzimidazoles and 7H‐Pyrrolo[1,2‐a]imidazoles
Authors: Knölker Hans‐Joachim , Boese Roland , Döring Detlev , El‐Ahl Abdel‐Aziz , Hitzemann Rainer , Jones Peter G. 
Published: July 2007

AbstractThe reaction of 1‐acylimidazoles with dialkyl acetylenedicar‐boxylates provides novel functionalized imidazole derivatives by a sequence of electrophilic attack on the imidazole azine nitrogen atom and subsequent transprotonations and trans‐acylations of the ylide generated in the first step. Based on this methodology we described a condensation of 1‐arylacetylimid‐azoles with DMAD in acetonitrile providing imidazo[1,2‐a]pyridines. We have now achieved a control of the cyclization mode leading to a different ring system simply by varying the acyl side chain. Solvent and reaction temperature influence these cyclizations strongly, thus allowing the preparation of further novel imidazole derivatives including the hitherto unknown furo[2′,3′:2,3]pyrrolo[1,2‐a]imidazole framework. Changing the parameters of the reaction of 1‐alkanoylimidazoles with electron‐deficient acetylenes allows the synthesis of (2‐imidazolyl)maleates 1,5‐dihydroimidazo[1,2‐a]pyridines, furo[2′,3′:2,3]pyrrolo[1,2‐a]imidazoles, furo[2′,3′: 2,3]pyrrolo[1,2‐a]benzimidazoles, and 7H‐pyrrolo[1,2‐a]imidazoles. The crystal structures of compounds 14a, 26, and 31d have been determined by X‐ray analysis.
Diallenylborane als Edukte für Borheterocyclen
Authors: Enders Markus , Pritzkow Hans , Siebert Walter 
Published: July 2007

Diallenylboranes as Starting Molecules for Boron HeterocyclesThe reaction of allenyllithium with chloro(dialkylamino)bornanes leads to the diallenylboranes 1, 2a, 3a, b, and 4 in 58–80% yield. Attempts to obtain the B‐tert‐butyl derivative 2b resulted in the formation of the unusual bicyclo compound 9. Heating of 1 in toluene gives the intermediate borole derivative 5, which dimerises to the Diels‐Alder product 5′. Reaction of 1 with (C5H5)Co(C2H4)2 leads to the cobalt‐borole complex 6. No 1,5‐H shift occurs on heating 2a and 3, respectively. Heating of 4 in mesitylene yields the dibora tricyclus 7, which undergoes a photochemical 1,5‐H shift to 8. Single crystal X‐ray structure determinations of 7, 8, and the complex 6 confirm their constitutions.
Radikalreaktionen an N‐Heterocyclen, X. Radikalreaktionen cyclischer 1,2‐Diacylhydrazine
Authors: Kluge Ralph , Schulz Manfred , Omelka Ladislav , Reinhardt Michael 
Published: July 2007

Free Radical Reactions of N‐Heterocyclic Compounds, X[1]. – Radical Reactions of Cyclic 1,2‐DiacylhydrazinesCyclic 1,2‐diacylhydrazyls 3 have been detected by ESR spectroscopy during oxidation of the corresponding NH compounds 2. The N coupling constants are determined and confirmed by simulation and by 15N labeling. The hydrazyls 3 react by dimerization to the corresponding tetrazanes of type 5 or by β scission to the diacyl azo compounds 4 and C radicals. The β scission of the radicals 3 is elucidated by UV/Vis detection of the azo compound 4b and reaction of 4b to Diels‐Alder adducts. The alkyl radicals are trapped by nitrosobenzene (8) (ESR).