bluuebunny/crossref_metadata_2025_split huggingface dataset:
Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXX. Insertions‐ und Additions‐Reaktionen an Diphosphamanganacyclopropanen mit aktivierten Alkinen
Authors: Lindner Ekkehard , Darmuth Monika , Mayer Hermann August , Fawzi Riad , Maichle Cäcilia , Steimann Manfred 
Published: July 2007

Metal‐;Containing Heterocycles: Preparation, Properties, Reactions, LXXX. — Insertion and Addition Reactions on Diphosphamanganacyclopropanes with Activated AlkynesThe thermally and kinetically stable diphosphamanganabicyclooctadienones 3a — e [R2 = tBu: R1 = iPr (a), nPr (b), Ph (c); R2 = Cy: R1 = nPr (d), Ph (e)] are obtained by the reaction of the alkyne (CCO2Me)2 with the diphosphamanganacyclopropanes (OC)4Mn‐PR=PR2 (2a — e). Depending on steric factors the formation of 3a — e occurs in two different ways. In a first step the alkyne is inserted into the P — P bond of 2a — e to give the kinetically labile five‐membered rings 1a — e. Subsequently another alkyne is added to the PR2 and a CO group of 1a — e to give 3a — e. In an alternative way the alkyne is added first to the PR2 and a CO group of 2a with formation of the diphosphamanganabicyclohexenone 4a. Insertion of a second alkyne into the P — P bond of 4a affords the bicyclooctadienone 3a. Compound 2a, 3c, and 4a have been characterized by X‐ray structural analyses.
Metallkomplexe in Biologie und Medizin, V. Neue Hydroxycarboxylat‐Komplexe von Bismut. Synthese und Struktur von Bismut(III)‐malat‐monohydrat und Bismut(III)‐tartrat‐trihydrat
Authors: Herrmann Wolfgang A. , Herdtweck Eberhardt , Scherer Wolfgang , Kiprof Paul , Pajdla Liba 
Published: July 2007

Metal Complexes in Biology and Medicine, V. — New Bismuth Hydroxycarboxylate Complexes. Synthesis and Structure of Bismuth(III) Malate Monohydrate and Bismuth(III) Tartrate TrihydrateReaction of Bi(NO3)3 · 5 H2O with L‐(–)‐malic acid results in the formation of bismuth(III) malate monohydrate Bi[O2CCH2CH(O)CO2] · H2O (1) containing the tridentate ligand [L‐(–)‐malate]3– with all donating functions deprotonated. By way of contrast, reaction of Bi(NO3)3 · 5 H2O with L‐(+)‐tartraic acid gives bismuth(III) tartrate trihydrate (2), in which two different tartrate ligands, [L‐(+)‐tartrate]1– and [L‐(+)‐tartrate]2– are present. The solid‐state structures have been determined by single‐crystal X‐ray methods and confirmed by powder diffraction measurements. The structure analyses exhibit a three‐dimensional network in the crystalline state resulting from bridging and chelating properties of the polydentate hydroxycarboxylate ligands. Bismuth shows high coordination numbers.
Selektive Ketonpyrolyse: Neue Beispiele
Authors: Ott Frank , Breitenbach JüRg , Nieger Martin , Vügtle Fritz 
Published: July 2007

Selective Ketone Pyrolysis: New ExamplesThe known ketone4, the new paracyclophane ketones6, 7, and9–12and the known hydrocarbons5, 8, and13are obtained by successive thermal extrusion of carbon monoxide from the [3n]paracyclophane(ones)n1, 2, and3(n= 2,3,4). The X‐ray structure analyses of the 20‐membered6and the 26‐membered ring10are reported.
Preparation of 3,4,5‐Trisubstituted 1,2,4‐Oxadiazolium Salts from Nitrilium Salts
Authors: Abu‐;El‐Halawa Rajab , Shrestha‐;Dawadi Prativa Bade , Jochims Johannes C. 
Published: July 2007

Abstract1,3‐Cycloadditions of stable nitrile oxides 2 to nitrilium salts 1 afford high yields of 3,4,5‐trisubstituted 1,2,4‐oxadiazolium salts 3. N‐Hydroxycarboximidoyl chlorides 4 add to nitrilium salts 1 to give isolable [(chloroalkylidene)aminooxyalkylidene]ammonium salts 5. A thermal stereomutation around the C = N+ bond is observed. On heating neat or in solution most compounds 5 cyclize to oxadiazolium salts 3. In cases where decomposition of 5 is faster than cyclization O‐silylated N‐hydroxycarboximidoyl chlorides 7 are treated with nitrilium salts 1 to furnish oxadiazolium salts 3.
Reversibility of the [2 + 2] Cycloaddition of Isocyanates to Glycals
Authors: Kaluża Zbigniew , Chmielewski Marek , Salański Piotr , Jurczak Janusz 
Published: July 2007

Abstract[2 + 2] Cycloadducts obtained by the addition of tosyl isocyanate to glycals (10 – 13) undergo retro‐addition upon heating or even at room temperature. The rate of retro‐addition increases with rising temperature and polarity of the solvent.
Organosubstituiertecis‐1,2‐Diborylalkene als elektrophile Chelatbildner
Authors: Köster Roland , Seidel Günter , Wagner Klaus , Wrackmeyer Bernd 
Published: July 2007

Organosubstitutedcis‐1,2‐Diborylalkenes as Electrophilic ChelatesTriethylborane (1), 9‐ethyl‐9‐borabicyclo[3.3.1]nonane (9‐ethyl‐9‐BBN) (2), and thecis‐1,2‐diborylalkenes (Z)1‐R2BC(R′)C(Et)BEt2[3: REt, R′Me;4: R,R′Et;5: REt, R′Ph;6: R2C8H14, R′Et;7: RPh, R′Et] react with alkali metal salts MX [MNa, K; XH, OMe, OtBu, OSiMe3, OSiEt3] in toluene to give the borates MX‐1, MX‐2, and the cycliccis‐1,2‐diborates M, resp., [e.g. KH‐3to KH‐7; NaOMe‐4to NaOMe‐6; KOtBu‐4, KOSiMe3‐4, KOSiEt3‐4] with BHB‐and B(OR)B‐bridges (IR, Multi NMR). Reaction of1, 2, and3–6with KCN leads to the monoborates KCN‐1, KCN‐2, and to the acycliccis‐1,2‐diborates KCN‐3to KCN‐7. — Thecis‐2‐Boryl‐1‐silylalkenes (E)1‐Me3SiC(R′)C(Et)BEt2[8: R′Me;9: R′Et] and KX [XH, CN, OMe] form the acyclic borates K[Me3SiC(R′)C(Et)1‐BEt2X]. The cyclic salts KOtBu‐4and KOSiEt3‐4undergo aB1‐substituent exchange to the acycliccis‐1,2‐diborates K[Et3BC(Et)C(Et)B(Et)OR] (K‐10: RtBu; K‐11: ROSiEt3).
Übergangsmetallaktivierte organische Verbindungen, XXXVIII. Chemoselektive nucleophile Methylierungen durch In‐Situ‐Blockierung von Aldehydgruppen unter α1‐Phosphonioalkoxid‐Bildung
Authors: Kauffmann Thomas , Abel Thomas , Li Weichang , Neiteler Gabriele , Schreer Martin , Schwarze Dieter 
Published: July 2007

Transition Metal‐Activated Organic Compounds, XXXVIII[1]. — Chemoselective Nucleophilic Methylation Reactions by In‐Situ‐Blocking of Aldehyde Groups by α1‐Phosphonioalkoxide FormationHerrn Professor Ulrich Schöllkopf zum 65. Geburtstag gewidmet.
For the selective methylation of a keto group in the presence of an aldehyde group the complex MeTiCl3·PPh3 and especially the reagent system [TiC]4·PPh3 + 0.5 Me2Zn] proved to be favourable. For instance, 6‐oxoheptanal (8) was methylated by [TiCl4·PPh3 + 0.5 Me2Zn] at the keto group with 89% yield and 99:1 selectivity, whereas it was methylated by [TiCl4 + 0.5 Me2Zn] at the aldehyde group with 81% yield and 96:4 selectivity. A selective methylation of benzaldehyde in the presence of heptanal was achieved with MeNbCl4·PPh3 or [NbCl5·PPh3 + 0.75 Me2Zn] to give (1‐chloroethyl)benzene (14; yield 92 or 53%; selectivity in each case 93:7) or with [TaCl5·PPh3 + 1.5 Me2Zn] to give mainly 1‐phenylethanol (15) besides 16. A 96:4‐selective benzylation (yield 74%) of a ketone in the presence of an aliphatic aldehyde was possible with [TiCl4·PPh3 + 1 PhCH2MgBr]. — The high chemoselectivity is caused by irreversible blocking of aliphatic aldehyde groups by α1‐phosphonioalkoxide formation[1], whilst the corresponding reaction of keto groups[1] and of benzaldehyde is reversible.
Synthese, Struktur und Reaktivität von Diphosphiranen
Authors: Streubel Rainer , Nieger Martin , Niecke Edgar 
Published: July 2007

Synthesis, Structure, and Reactivity of DiphosphiranesThe 1,1‐diamino‐1,2‐diphospha‐2‐propen (2,6‐Me2C5H8N)2P – PC(SiMe3)2 (3) is obtained by treatment of bis(2,6‐dimethyl‐piperidino)(trimethylsilyl)phosphane (1) with [bis(trimethylsilyl)methylene]chlorophosphane (2). Compound 3 readily undergoes thermally isomerization to the diphosphirane 2,6‐ Nucleophilic substitution of the P1‐chloro function of 1‐chloro‐2‐(diisopropylamino)1‐3,3‐bis(trimethylsilyl)diphosphirane (6) leads to alkyl, amino, phosphanyl, and arsanyl derivatives 7a – d. The corresponding hydrogen derivative 7e is formed by reduction of 6 with tri‐n1‐butylstannane. The molecular structure of 7c as well as the NMR data of the diphosphiranes are discussed.
Neue Beiträge zur Chemie des Mangans: Synthese und Strukturen zweier monomerer MnII1‐Verbindungen und eines hexanuklearen MnII/III1‐Komplexes
Authors: Köhler Katrin , Roesky Herbert W. , Noltemeyer Mathias , Schmidt Hans‐Georg , Freire‐Erdbrügger Cristina , Sheldrick George M. 
Published: July 2007

New Contributions to the Chemistry of Manganese: Syntheses and Structures of two Monomeric MnII Compounds and a Hexanuclear MnII/III ComplexTwo novel mononuclear manganese(II) complexes, Mn[OSi(OtBu)3]2·(Py)3 (2) and Mn[PhC6H4C(NSiMe3)2]2·THF (3), and a hexanuclear mixed‐valence manganese(II/III) complex Mn6O2(O2CtBu)10·(Py)4 (5) have been prepared, and their structures have been determined by X‐ray crystal structure analyses.
Highly Strained Cage Compounds from a Fourfold Bridged Tricyclo[4.2.0.02,5]octa‐3,7‐diene
Authors: Gleiter Rolf , Pflästerer Georg , Irngartinger Hermann 
Published: July 2007

AbstractThe fourfold bridged tricyclo[4.2.0.02,5]octa‐3,7‐diene derivative 3 reacts with diazomethane and m1‐chloroperbenzoic acid (mCPBA) to yield the monoadduct 5 in good and the bisadduct 4 in poor yield as well as the mono‐and bisepoxides 7 and 8 in good yields, respectively. Also the “mixed” product 6 is obtained. All five compounds are strained propellanes. The X‐ray crystallographic structure analysis of 8 reveals a distance of 2.812 Å between the epoxide rings.
Mono‐, Di‐, Tri‐, Tetra‐, Penta‐und Hexaphenylbullvalene
Authors: Rebsamen Karl , Röttele Herbert , Schröder Gerhard 
Published: July 2007

Mono‐, Di‐, Tri‐, Tetra‐, Penta‐and HexaphenylbullvalenesLithium diphenylcuprate reacts with the corresponding bromobullvalenes to yield the phenylbullvalenes 1–6, whose substitution patterns are deduced from their 1H‐NMR spectra. Starting with triphenylbullvalenes 3 some isomers show a relatively high kinetic stability which culminates in the case of the hexaphenylbullvalenes 6a and 6b in the loss of the phenomenon of fluctuating structure for the bullvalene skeleton.
Alkyleisen‐und Alkylcobalt‐Reagenzien, VIII. Eisen(II)1‐alkyle als Reagenzien und Katalysatoren für die Überführung von Acylchloriden in Ketone
Authors: Kauffmann Thomas , Voß Karl‐Uwe , Neiteler Gabriele 
Published: July 2007

Alkyliron and Alkylcobalt Reagents, VIII[1]. – Alkyl‐Iron(II) Compounds as Reagents and Catalysts for the Transformation of Acyl Chlorides into KetonesMe2Fe, Bu2Fe, Me3FeLi, or Bu3FeLi – prepared in situ by reduction of FeCl3 to FeCl2 and subsequent alkylation with MeLi, MeMgBr, BuLi, or BuMgBr – are useful reagents for the conversion of acyl chlorides into ketones. The system (RMgX + catalytic amount of FeCl3) react like the alkyl FeII reagents with acyl chlorides to give ketones even at –65°C. Competition experiments with benzoyl chloride/2‐methoxy‐benzoyl chloride show that the selectivity increases (competition constants Kk9.9, 10.7, 10.9, 15.0, ca. 110) in the sequence MeFeCl, Me2Fe, Me3Fe(MgBr), Me4Fe(MgBr)2, and catalytic system [MeMgBr + 2.5 mol % FeCl3] (= 2, 3, 4, 5, and 40 MeMgBr per 1 FeCl3, respectively). A new hypothesis on the nature of the active catalyst is discussed.
Ein weiterer Beitrag zur Stabilisierung der Iminoborane RB≡NR′
Authors: Kiesgen Jutta , Münster Jochen , Paetzold Peter 
Published: July 2007

A Further Contribution to the Stabilization of Iminoboranes RB≡NR'The iminoboranes (tBuB≡NR (1a, b, R=iPr, Ph) and RB≡NR (1c, d; R=Me3CCH2, Me3SiCH2) were prepared by gas‐phase thermolysis of Cl(tBu)BN(R)SiMe3 (6a, b) and R2BN3 (7c, d), respectively. At room temperature, the molecules 1a–c cyclodimerize to the diazadiboretidines 2a–c, whereas the borane 1d cyclotrimerizes to the borazine 3d; these stabilization reactions are discussed in terms of the steric demand of the organic ligands. The ethyloboration of 1a, c with BEt3 BCl to 1a yields the diborylamine 9d. Benzyl azide and 1c, d undergo a [3 + 2] cycloaddition with formation of the tetrazaborolidines 10c, d.
Electroorganie Synthesis, 55[1]. Influences on the Selectivity of the Kolbe versus the Non‐Kolbe Electrolysis in the Anodic Decarboxylation of Carboxylic Acids
Authors: Klocke Elisabeth , Matzeit Agnes , Gockeln Marianne , Schäfer Hans J. 
Published: July 2007

AbstractThe anodic decarboxylation of 3‐oxanonanoic acid (2a) and 3‐oxapentadecanoic acid (2b) in methanol leads exclusively to products of the non‐Kolbe electrolysis. The influence of co‐electrolysis, solvent, current density, degree of neutralization and chain length of the alkoxy group on the anodic decarboxylation of 2a, b have been investigated. An extended alkyl chain in the alkoxy group, coelectrolysis with long‐chain fatty acids, ethanol or dimethylformamide as solvent, and a high current density favor the Kolbe coupling against the non‐Kolbe electrolysis.
Cycloaddition Reactions Initiated by Photochemically Excited Pyrylium Salts
Authors: Martiny Martin , Steckhan Eberhard , Esch Thomas 
Published: July 2007

AbstractSeveral pyrylium, thiapyrylium, and pyridinium salts have been synthesized and used as sensitizers for photochemically induced electron‐transfer (PET) reactions. The salts have been tested in the mixed cycloaddition reactions of styrenes 9 with 1,3‐cyclohexadiene (8) or 1,1'‐dicyclohexenyl (23). In the case of the PET [4 + 2] cycloaddition of styrene (9a) to 1,3‐cyclohexadiene (8), the reaction takes place via the cation radical of the diene. When chloroform instead of dichloromethane is used as the solvent, only [2 + 2] cycloaddition products are obtained. In contrast, if 1,3‐cyclohexadiene (8) is replaced by 1,1'‐dicyclohexenyl (23), the key step of the reaction seems to be the oxidation of styrene (9). The product ratios depend on the sensitizers used. If solvent‐separated ion pairs are formed, styrene reacts as diene to give 1‐cyclohexenyloctahydro‐phenanthrene derivatives 28; cycloaddition via contact ion pairs leads to the Diels‐Alder product with styrene acting as the dienophile.
Flüssigkristalline Verbindungen, 79[1a]. Amphiphile und mesogene Kohlenhydrate, V[1b]. Amphiphile Fluorglucose‐ und Fluorscyllitol‐Derivate
Authors: Miethchen Ralf , Prade Heiko , Holz Jens , Praefcke Klaus , Blunk Dirk 
Published: July 2007

Liquid Crystalline Compounds, 79[1a].–Amphiphilic and Mesogenic Carbohydrates, V[1b].–Amphiphilic Fluoroglucose and Fluoroscyllitol DerivativesIn order to look at the influence of the OH‐F substitution in the cyclic, hydrophilic section (head group) of amphiphilic sugars and of scyllitol derivatives on their liquid crystalline properties for the first time, we synthesized various differently structured fluoro‐D‐glucose derivatives [2‐O‐decyl‐α‐D‐glucopyranosyl fluoride (4), 4‐O‐tetradecyl‐α‐D‐glucopyranosyl fluoride (5), 6‐O‐hexadecyl‐α‐D‐glucopyranosyl fluoride (6), 6‐deoxy‐6‐fluoro‐2,3‐di‐O‐hexadecyl‐D‐glucopyranose (9), 2‐deoxy‐2‐fluoro‐4,6‐O‐alkyliden‐D‐glucopyranosen (11a–d), 3‐deoxy‐3‐fluoro‐5,6‐di‐O‐tetradecyl‐D‐glucofuranose (15)] as well as the 2‐deoxy‐2‐fluoro‐2,3,4,5,6‐tetra‐O‐hexyl‐scyllo‐in‐osit (19). Substitution of an OH group for a fluorine atom in amphiphilic derivatives destabilizes the thermotropic mesophase as it was to be expected so that either no or only narrowrange mesophases result. Both thermotropic and lyotropic liquid crystal phases occur in the series of 2‐deoxy‐2‐fluoro‐D‐glucopyranose acetals 11 which are discussed in detail and which are compared with the analogous 2‐hydroxy derivatives 12. Only 11c–d are thermotropic fluoro mesogens.
Auf dem Weg zu makrocyclischen para‐Phenylenen
Authors: Friederich Rolf , Nieger Martin , Vögtle Fritz 
Published: July 2007

On the Way to Macrocyclic para‐PhenylenesStrategies are presented to synthesize the hitherto unknown [On]Paracyclophanes 1. Open chain belt‐type molecules based on 1,4‐connected carbocyclic six‐membered rings were prepared. Functionalization of the outer rings in 4‐position is the prerequisite for cyclization or lengthening of the molecular belts. In order to obtain the macrocyclic target molecules 1, well preorganized cis‐isomers of 1,4‐disubstituted cyclohexanes were prepared. X‐ray structural analyses reveal the static stereochemistry of the intermediates 8, 9, 17, 18, and 24. The macrocyclic hydrocarbon 29 containing five cyclohexylidene units was detected.
Solvolysis of Tricyclo[3.1.0.02,6]hex‐3‐yl and Bicyclo[2.1.1]hex‐2‐yl Sulfonates
Authors: Bentley T. William , Norman Simon J. , Gerstner Erwin , Kemmer Ralf , Christl Manfred 
Published: July 2007

AbstractSolvolyses of cis‐tricyclo[3.1.0.02,6]hex‐3,4‐diyl ditosylate (12) and cis‐bicyclo[2.1.1]hex‐2,3‐diyl ditosylate (27) have been carried out in 80% aqueous ethanol in the presence of ethyl‐diisopropylamine. In the former case, endo,endo‐tricyclo[2.2.0.02,6]hexane‐3,5‐diol (13a), its monoether 13b and diether 13c were products whereas in the latter the monoethers 28b, d, e, g and the diethers 28a, c, f of bicyclo[3.1.0]hexane were formed. In pure ethanol, 12 was converted into pure 13c in good yield. In the presence of the weaker base 2,6‐lutidine, the solvolysis of 12 in aqueous ethanol gave different products, i.e. exo,exo‐4,6‐diethoxybicyclo[3.1.0]hex‐2‐ene (14a) and several aldehydes, inter alia cyclopentadiene‐1‐carboxaldehyde (15). In control experiments, the tricyclic compounds 13b, c were converted into 14a, 15 and further aldehydes as well as into the bicyclo[2.1.1]hexene derivatives 19a, b. Sulfonates of tricyclo[3.1.0.02,6]hexan‐3‐ol (21a) could not be isolated but its mesylate 21c was characterized by NMR spectroscopy and hydrolysed in aqueous acetone to give tricyclo[2.2.0.02,6]hexan‐endo‐3‐ol (22a). It is concluded from these results that the dissociations of the above sulfonates do not lead to unrearranged carbocations. Rather, they proceed with participation of the β‐carbon in trans position relative to the leaving group resulting in the immediate generation of rearranged cations.–Kinetic studies show that the tricyclic mesylate 21c solvolyses in 80% ethanol/water 1.4 · 105 times as fast as bicyclo[2.1.1]hex‐2‐yl tosylate (25), and the tricyclic ditosylate 12 solvolyses 6 · 105 as fast as the corresponding bicyclic ditosylate 27. These rate enhancements are similar to those previously observed for less strained cyclopropylcarbinyl substrates.
Cyclopropanierung von Fullerenen
Authors: Bingel Carsten 
Published: July 2007

Cyclopropylation of FullerenesCyclopropylation of fullerenes C60 and C70 is achieved by a tandem process. Michael addition of a stabilized α‐halocarbanion to fullerenes followed by intramolecular substitution of the halogen yields fullerene derivatives with functional groups.
Derivate des Imidazols, VI. Stabile Carben‐Borane
Authors: Kuhn Norbert , Henkel Gerald , Kratz Thomas , Kreutzberg Jörg , Boese Roland , Maulitz Andreas H. 
Published: July 2007

Imidazole Derivatives, VI[1]. — Stable Carbene BoranesStable imidazol‐2‐ylidene—borane adducts 8 and 9 are obtained from 1,3,4,5‐tetraalkylimidazol‐2‐ylidenes 7 and Me2S BH3 or Et2O BF3. An X‐ray structure analysis of 8b has been performed. An ab initio calculation [MP2(fu)/6–31G**] reveals a low energy difference between two rotamers. The bond orders of the cyclic bonds imply only a minor interaction between the N—C—N and the C—C fragment.
Direct Observation and Trapping of a Heterocyclic α‐Oxo Ketene: 3‐Carbonyl‐1,3‐dihydro‐1‐methyl‐2H‐indol‐2‐one
Authors: Kappe Thomas , Oliver Kappe C. , Wentrup Curt , Färber Gerald 
Published: July 2007

AbstractThe title compound 8a was generated by both flash vacuum pyrolysis and matrix photolysis of diazoquinolone 7 and identified by Ar‐matrix IR spectroscopy and mass spectrometry. Trapping of the highly reactive α‐oxo ketene 8a with methanol leads to β‐keto ester 9, whereas dimerization of 8a furnishes spiro compound 10.
Oxidation von Bis[2,4,6‐tris(trifluormethyl)phenyl]stannandiyl mit Triplett‐ und komplex gebundenem Disauerstoff
Authors: Grützmacher HansjÖRg , Pritzkow Hans 
Published: July 2007

Oxidation of Bis[2,4,6‐tris(trifluoromethyl)phenyl]stannanediyl by Triplet and Complex‐Bound DioxygenHomogeneous oxygenation of the stannanediyl [2,4,6‐(CF3)3C6H2]2Sn (15) by molecular triplet oxygen in toluene solution or heterogeneously in the solid state leads to the formation of the cyclotristannoxane 17. In a pure oxygen matrix 15 does not react either thermally (10–45 K) or photochemically. Upon treatment of 15 with the dioxygen complex (Ph3P)2Pt(O2) (16) a stable five‐membered Pt–Sn–O ring 18 is obtained which is a rare example of a covalently linked main group metal‐transition metal heterocycle. The oxygenation products 17 and 18 were characterized by X‐ray structure analyses which revealed the non‐planarity of both heterocycles.
Metallkomplexe mit biologisch wichtigen Liganden, LXVII[1]. Synthese von α‐Aminosäuren aus Palladium(II)‐ und Rhodium(III)‐koordinierten Iminen und Oximen von α‐Oxocarboxylaten
Authors: Krämer Roland , Wanjek Herbert , Polborn Kurt , Beck Wolfgang 
Published: July 2007

Metal Complexes of Biologically Important Ligands, LXVII[1]. – Synthesis of α‐Amino Acids from Palladium(II)‐ and Rhodium(III)‐Coordinated Imines and Oximes of α‐OxocarboxylatesThe bis‐chelate complexes Pd[O2CC(R1)=NOR2]2 (1) and Pd[O2CC(R1)=NR2]2 (2, R2 optically active substituent) are synthesized by template condensation of an α‐oxocarboxylic acid with a hydroxylamine or amine component, respectively. Similarly, the Rh(III) complexes Cp*Rh(Cl)[O2CC(R)=N(CHMePh)] (3a: R = H, 3b: R = Me) were obtained from α‐oxocarboxylic acids and optically active 1‐phenylethylamine. Catalytic hydrogenation of 1 and 2 gives directly the free α‐amino acids with, in case of 2, ee's between 0 and 36%. Nucleophilic attack by the carbanions of RC(O)CH2CO2Et and H2NCH(CO2Et)2 at the imino carbon atom of 3a leads to the α‐amino carboxylato complexes 4 and 5. – Compounds 4a and 5 have been characterized by X‐ray diffraction. Reaction of 3a with NaBH4 or NaBD4 followed by decomposition of the complex with HCl yields N‐substituted glycine and N‐substituted α‐deuterio‐glycine, respectively. The diastereoselectivity (70:30) of the α‐deuteration could be determined by NMR spectroscopy.
Organophosphorverbindungen, 73. Der Tri‐tert‐butyl‐2‐cyclopropen‐1‐yl‐Rest als kinetisch stabilisierende Gruppe für 1‐Aza‐3‐phosphaallene
Authors: Wegmann Thomas , Hafner Michael , Regitz Manfred 
Published: July 2007

Organophosphorus Compounds, 73[1]. – The Tri‐tert‐butyl‐2‐cyclopropen‐1‐yl Substituent as Kinetically Stabilizing Group for 1‐Aza‐3‐phosphaallenes[2]The cyclopropenylphosphane 5 reacts with the isocyanates 6a–g to form the phosphaalkenes 7a–g. An analogous transformation occurs with the same phosphane and the bifunctional isocyanates 8a, b (→ 9a, b). In contrast, the reaction 5 + 6h ends at the stage of the tautomers 11h ⇆ 12h. Methanolysis of 7b and of 11h ⇆ 12h leads to the carbamoyl‐cyclopropenylphosphanes 14a and b, respectively. Sodium hydroxide‐catalyzed elimination of hexamethyldisiloxane from 7b, g and the tautomer mixture 11h ⇆ 12h yields the target 1‐aza‐3‐phosphaallenes 16a–c.
Chlorthiatriazine
Authors: Chen Shan‐Jia , Mews Rüdiger , Behrens Ulrich , Fischer Eberhard , Pauer Frank , Sheldrick George M. , Stalke Dietmar , Stohrer Wolf‐Dieter 
Published: July 2007

ChlorothiatriazinesFrom (ClSN)3 (1) and ClCN (2) 1,3,5‐trichloro‐1,3,2,4,6‐dithiatriazine (ClCN)(ClSN)2 (3) was prepared in 26% yield. 3 reacts slowly further with excess 2 to give thiatriazine (ClCN)2(ClSN) (14) and triazine (ClCN)3 (16). A mechanism for the (ClSN)/(ClCN) exchange is proposed. The structures of 3, 14, and 16 have been determined by X‐ray diffraction. The bonding situation in the system (ClSN)n(ClCN)3–n (n = 0 – 3) is discussed.