bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intramolecular, Metallacyclic Organoaluminium, ‐gallium and ‐indium Addition Compounds Crystal Structure of 1‐Galla‐5‐azabicyclo[3.3.3]undecane
Authors: Schuman Herbert , Hartman Uwe , Wassermann Wilfried , Just Oliver , Dietrich Andreas , Pohl Ludwig , Hostalek Martin , Lokai Matthias 
Published: July 2007

AbstractIntramolecularly base‐stabilized four‐coordinated metallacyclic organoaluminium, ‐gallium, and ‐indium compounds C5H10‐Al(CH2)3NMe2 (4), C4H8Ga(CH2)3NMe2 (5), C5H10Ga(CH2)3N‐Me2 (6), C5H10GaCH2CH(Me)CH2NMe2 (7), C4H8Ga(CH2)4NMe2 (8), C5H10Ga(CH2)4NMe2 (9), EtAl[(CH2)3]2NMe (10), MeGa‐[(CH2)3]2NMe (11), EtGa[(CH2)3]2NMe (12), MeIn[(CH2)3]2NMe (13), and (14) have been synthesized by the reaction of [3‐(dimethylamino)propyl]aluminium dichloride (1), [3‐(dimethylamino)propyl]gallium dichloride (2), [3‐(dimethylamino)‐2‐methylpropyl]gallium dichloride (3), or [4‐(dimethylamino)butyl)gallium dichloride with the respective bis‐Grignard reagents or by the reaction of the organometal dichlorides RMCl2 with bis[3‐(chloromagnesio)propyl]methylamine or with N,N′‐bis[3‐(chloromagnesio)propyl]‐N,N′‐dimethyl ethylenediamine. Aluminium or gallium trichloride reacts with tris[3‐(chloromagnesio)propyl]amine to give Al[(CH2)3]3N (15) and Ga[(CH2)3]3N (16). The 1H‐, 13C‐NMR and mass spectra of the new compounds as well as the X‐ray crystal structure of 16 are discussed. 4, 6, and 12 have been tested successfully as MOVPE precursors.
Synthesis of Optically Active Bis(2‐oxazolines): Crystal Structure of a 1,2‐Bis(2‐oxazolinyl)benzene ZnCl2 Complex
Authors: Bolm Carsten , Weickhardt Konrad , Zehnder Margareta , Ranff Tobias 
Published: July 2007

AbstractDinitriles (5–7, 12, 13) react with enantiomerically pure β‐amino alcohols (8 – 11,17) under zinc chloride catalysis to give optically active C2‐symmetric bis(oxazolines). 1,2‐Bis(2‐oxazolin‐2‐yl)benzenes 1a – e are obtained under mild reaction conditions. 1H‐NMR spectroscopy indicates the formation of 1:1 complexes 23 of these compounds with ZnCl2. The energy required for a conformational interconversion of zinc dichloride complex 23e was determined by variable‐temperature 1H‐NMR studies. An X‐ray structure analysis was performed with the substituted [1,2‐bis(2‐oxazolinyl)benzene]zinc dichloride complex 23a.
Azobrücken aus Azinen, XII. Transannulare Hydroborierung von parallel benachbarten CC/NN‐Bindungen
Authors: Brand Uwe , Hünig Siegfried , Peters Karl , Schnering Hans Georg Von 
Published: July 2007

Azo Bridges from Azines, XII., – Transannular Hydroboration of Close Parallel CC and NN BondsIn the systems 3 and 5 9‐borabicyclo[3.3.1]nonane (9‐BBN) adds to the close parallel CC/NN bonds in a transannular reaction. A B – N bond is formed and the borane hydrogen transferred to the CC bond regio‐ and stereospecifically. The structure of the adducts 4 and 6 is elucidated by NMR spectroscopy and in the case of 4a by an X‐ray analysis. The catecholborane 9 forms with 3 an azo – borane adduct at first, pointing to a stepwise transannular reaction.
Ring – Chain Tautomerism of 4‐Hydroximino‐hexahydropyrimidines Substituted in Position 2
Authors: Korbonits Dezsö , Tóbiás‐Héja Erzsébet , Kolonits Pαl 
Published: July 2007

AbstractAs shown by NMR spectroscopy, the reaction of 3‐aminopropionamide oxime (9) with benzaldehyde or benzaldehyde derivatives 2a–d substituted with electron‐attracting substituents affords products which exist as an equilibrium mixture of tautomers involving the open‐chain 3‐(benzylideneamino)‐propionamide oximes 11a – d and the cyclic 4‐hydroximinohexahydropyrimidines 12a – d. Tautomers 11 and 12, isolated also in crystalline form, can be interconverted by using an appropiate solvent. In contrast, in the reaction of benzaldehydes substituted with electron‐releasing groups (2e, f) and cinnamaldehyde (2g) with 9 only the open‐chain imines are formed, and in aprotic solvents no tautomerism can be observed.
Organische Synthesen mit übergangsmetall‐Komplexen, 51. 1‐Metalla‐1,3,5‐triene und 1‐Metalla‐1,3‐dien‐5‐ine von Chrom und Wolfram durch Insertion von Alkinen in MC‐ bzw. CC‐Bindungen von 1‐Metalla‐1,3‐dienen bzw. 1‐Metalla‐1‐en‐2‐inen
Authors: Aumann Rudolf , Heinen Heinrich , Hinterding Peter , Str äter Norbert , Krebs Bernt 
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 51. – 1‐Metalla‐1,3,5‐trienes and 1‐Metalla‐1,3‐dien‐5‐ynes of Chromium and Tungsten by Insertion of Alkynes into MC and CC Bonds of 1‐Metalla‐1,3‐dienes and 1‐Metalla‐1‐en‐3‐ynes, respectively1‐Metalla‐1,3,5‐trienes LnMC(NEt2)–C(Me)C(OEt)–CHCHPh (3,4) and LnMC(OEt)– CHC(NEt2) – C(Me)=CHPh [5, LnMCr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1‐metalla‐1,3‐dienes LnMC(OEt) – CHCHPh (1a, b) under very mild conditions by the insertion of the electron‐rich alkyne Et2N–C  C – Me (2) into the MC and the CC bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1‐Metalla‐1,3‐dien‐5‐ynes LnMC(NEt2) – C(Me)=C(OEt) – C  CPh [9, 10, LnMCr(CO)5 (a), W(CO)5 (b)] are formed with high regio‐ and stereoselectivity on insertion of 2 into the MC bonds of 1‐metalla‐1‐en‐3‐ynes 8. X‐ray data are given for the tungsten complex 3b.
Alkine und Cumulene, XXIII. über einige Neben‐ und Folgeprodukte der Dichlorketen‐Herstellung aus α,α‐Dichloracetylchlorid
Authors: Hopf Henning , Stamm Reiner , Jones Peter G. 
Published: July 2007

Alkynes and Cumulenes, XXIII. – On Some Byproducts of the Dichloroketene Preparation from α,α‐Dichloroacetyl ChlorideWhen α,α‐dichloroacetyl chloride (1) is dehydrochlorinated with triethylamine in refluxing ether, two oligomers are obtained: 1‐dichloroacetoxy‐1‐dichloromethyl‐2,2‐dichloroethylene (3) and octachloro‐1,2‐bis(methylene)cyclobutane (4). The mechanisms of formation of these tri‐ and tetrameric products of 1 and dichloroketene (2), respectively, are discussed, and an X‐ray structural analysis of 4 is reported.
Synthese und Kristallstruktur von Li2[(Me3SiCH2)3AlCH2Al(CH2SiMe3)3] — ein Addukt des Dilithiomethans CH2Li2?
Authors: Uhl Werner , Layh Marcus , Massa Werner 
Published: July 2007

Synthesis and Crystal Structure of Li2[(Me3SiCH2)3AlCH2Al(CH2SiMe3)3]—a Dilithiomethane Derivative?Reaction of (trimethylsilyl)methyllithium with the methylene‐bridged aluminium tetrachloride Cl2AlCH2AlCl2 yields dilithium methylenebis[tris(trimethylsilylmethyl)aluminate] (2) as the only isolable product. All attempts for preparing the tetraalkyl analogue have been unsuccessful. The crystal structure of 2 exhibits a hexacoordinated central carbon atom with short LiC distances. Both lithium atoms and the methylene hydrogens of the AlCH2 Al unit are almost coplanar. The discussion of the structure and properties leads to the attractive description of 2 as an adduct of tris(trimethylsilylmethyl)‐aluminium to dilithiomethane CH2Li2.
Umwandlung der Cluster Fe3(CO)9(μ3‐η2‐N2Et2) und Fe3(CO)9(μ3‐NEt)2 zu organischen Produkten 1)
Authors: Tasi Miklos , Powell Anne K. , Vahrenkamp Heinrich 
Published: July 2007

Conversion of the Clusters Fe3(CO)9(μ3‐η2‐N2Et2 and Fe3(CO)9(μ3‐NEt)2 into Organic ProductsThe azoalkane‐bridged cluster Fe3(CO)9(μ3‐η2‐N2Et2) (1) and its thermal rearrangement product Fe3(CO)9(μ3‐NEt)2 (2) are converted by standard routes into derivatives with one carbene ligand C(Ph)OEt (3, 4). Degradation (thermally or oxidatively) of these compounds produces the diaziridine magnified image (5) and/or the iminoester EtN = C(Ph)OEt (6). 4 and moist p‐tolyl isocyanide form the indole derivative 8. 1 adds one or two equiv. of alkynes leading to the alkyne‐bridged cluster 9 or the ferrole‐type clusters 10. The clusters 10, resulting from HCCPh, exist as two isomers 10a and b which can be equilibrated and separated. An alternative route to 10 c (alkyne: MeCCMe) starts from Fe2(CO)6(C4Me4) by treating it with Fe2(CO)9 and N2Et2. Photolytic or oxidative degradation of the clusters 10 produces substituted furan 13, pyrrole 14, or dihydropyridazine 15. The crystal structures of the clusters 4, 9, 10a, and 10b have been determined.
Complexes with sterically demanding ligands, XVI. An unexpected coupling of trimethylsilyl‐substituted cyclopentadienide anion by ferric chloride
Authors: Okuda Jun , Herdtweck Eberhardt , Zeller Edgar M. 
Published: July 2007

AbstractReaction of 1,2,4‐tris(trimethylsilyl)cyclopentadienyllithium with ferric chloride in THF at ‐95°C leads to the formation of a thermally sensitive iron(III) complex which decomposes to the new dihydrofulvalene derivative 3,7‐dihydro‐1,3,3,5,7,7‐hexakis(trimethylsilyl)fulvalene (1).
Reaktionen von Komplexliganden, XLIII. Optisch aktive Aminocarben‐Komplexe: Reagentien für die regiospezifische und diastereoselektive Synthese von γ‐Lactamen
Authors: Dötz Karl Heinz , Weber Rita 
Published: July 2007

Reactions of Complex Ligands, XLIII. ‐ Optically Active Aminocarbene Complexes: Reagents for the Regiospecific and Diastereoselective Synthesis of γ‐LactamsOptically active pentacarbonyl[amino(aryl)carbene] complexes 2 ‐ 5 of chromium have been obtained by aminolysis of methoxycarbene complexes 1 with L‐amino acid esters. The alanyl and phenylalanyl compounds 2, 3 react with 1‐octyne regiospecifically and moderately diastereoselectively to give the pyrrolinones 6, 7.
Darstellung O‐geschützter (R)‐2‐Hydroxyaldehyde und ihre Hydrocyanierung
Authors: Effenberger Franz , Hopf Martin , Ziegler Thomas , Hudelmayer Jochen 
Published: July 2007

Synthesis of O‐Protected (R)‐2‐Hydroxy Aldehydes and Their HydrocyanationThe synthesis of O‐silyl‐ and O‐benzyl‐protected (R)‐2‐hydroxy aldehydes (R)‐6 from (R)‐2‐hydroxy carboxylic acids (R)‐1 is described. While attempts for their diastereoselective hydrocyanation with hydrocyanic acid and (R)‐oxynitrilase as catalyst have not been successful, the cyano silylation with trimethylsilyl cyanide occurred diastereoselectively with a ratio of 81 : 19 preferring the threo form without racemization at C‐2 of the 2‐hydroxy aldehyde.
Kurzmitteilung/Short Communication Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXV Synthese eines Diphosphamolybdacyclopentens durch Alkin‐Insertion in die P—P‐Bindung eines Diphosphamolybdacyclopropans
Authors: Lindner Ekkehard , Heckmann Maria 
Published: July 2007

Metal‐Containing Heterocycles: Preparation, Properties, Reactions, LXXV1). — Synthesis of a Diphosphamolybdacyclopentene by Alkyne Insertion into the P ‐ P Bond of a DiphosphamolybdacyclopropaneInsertion of the alkyne RCCR (R = CO2Me) into the P ‐ P bond of the diphosphamolybdacyclopropane (5‐C5H5)‐(OC)2Mo‐PPh2‐PAr (2) [Ar = 2,4,6‐(tBu)3C6H2] results in the formation of the thermally and kinetically stable diphosphamolybdacyclopentene (η5‐C5H5)(OC)2Mo‐PPh2‐RC = CR‐PAr (3), which is characterized on the basis of mass, IR, 31P{1H}‐, 1H‐, and 13C{1H}‐NMR spectra.
Stable N‐Phosphanyl Nitrilimines: Reactivity on the Periphery of the Nitrilimine Skeleton
Authors: Castan Florence , Granier Michel , Baceiredo Antoine , Bertrand Guy , Straw Thomas A. , Dillon Keith B. 
Published: July 2007

AbstractReactions involving the λ3‐phosphorus atom of N‐[bis(diisopropylamino)phosphanyl)]‐C‐[(bis(diisopropylamino) ‐thio‐phosphoranyl)nitrilimine (1) are reported. Addition of elemental sulfur or selenium to 1 leads, by a formal [1 + 4] cycloaddition, to 1,3,4,2λ5‐thiadiazaphosphole 3a or 1,3,4,2λ5‐selenodiazaphosphole 3b in 85 and 84% yield, respectively. Reactions of 1 with dimethyl acetylenedicarboxylate and tetracyanoethylene afford the corresponding [2 + 4] adducts 1,2,3λ5‐diazaphosphinine 6 (80% yield) and 1,2,4,3λ5‐triazaphosphinine 10 (80% yield). Phenyl azide reacts with 1 with loss of nitrogen to give 1,2,4,3λ5‐triazaphosphole 15 (74% yield), while the reaction of 1 with α‐diazo ketone 17 leads with conservation of the N2 grouping to the formation of 1,2,4,3λ5‐triazaphosphole 20 (85% yield). Addition of methyl trifluoromethanesulfonate to 1 affords N‐[bis(diisopropylamino)methylphosphonioyl]‐C‐[bis(diisopropylamino)thiophosphoranyl]nitrilimine 22. In contrast to 1, the new stable nitrilimine 22 is strongly electrophilic. [2 + 3] cycloadditions are observed with ethyl vinyl ether, styrene, methyl acrylate and phenylacetylene to furnish the corresponding pyrazolines 23 – 25 and pyrazole 26 in good yields. Water adds to 22 by a 1,3‐addition process to give hydrazine 27 (88% yield). The lithium salt 30 of [bis(diisopropyl‐amino)thiophosphoranyl](diazo)methane reacts with [bis(pentafluorophenyl)](chloro)phosphane to afford the corresponding diazo compound 32 (50% yield) while the reaction with (chloro)(phenyl)[2,4,6‐tris(trifluoromethyl)phenyl]phosphane furnishes nitrilimine 33 in 82% yield. Only 1,3‐addition reactions with water or diisopropylamine leading to hydrazine 34 (65% yield) and hydrazone 35 (54% yield) are observed on treatment with this new poorly reactive nitrilimine.
Photolysis of Tetraalkyl‐1‐pyrazoline‐4‐thiones. – Diastereoselective Formation of (E)/(Z)‐Alkylidenethiiranes from cis‐ and trans‐Tetraalkyl‐1‐pyrazoline‐4‐thiones
Authors: Quast Helmut , Fuß Andreas , Jakobi Harald 
Published: July 2007

AbstractThe tetraalkyl‐1‐pyrazolin‐4‐ones 5 react with hydrazine to afford the hydrazones 6 which are transformed into the thiones 7 in high yields by treatment with disulphur dichloride in the presence of triethylamine. Selective excitation of the azo chromophor of 7a with 350‐nm light gives rise to the isopropylidenethiirane 8, besides molecular nitrogen, in a very clean reaction; at almost quantitative conversions, less than 2% of byproducts are observed, and about 10% of 8 have isomerized to the pentadienethiol 9. Photolysis of the stereoisomers cis‐ and trans‐7b yields mixtures of the alkylidenethiiranes (E)‐and (Z)‐10 with (E)/(Z) ratios of 35:65 and 49:51. The results are interpreted in terms of diastereomeric bis‐orthogonal (cis‐ and trans‐21) and mono‐orthogonal thioxyallyl diradicals (E)‐ and (Z)‐23 which cyclize to furnish (E)‐ and (Z)‐10. There seems to be a qualitative resemblance between the photochemical and thermal stabilities in the series of 4‐substituted tetramethyl‐1‐pyrazolines, viz. 7a < 12 < 5a, 13, similar to that suggested by Engel for 2,3‐diazabicyclo[2.2.2]oct‐2‐ene derivatives.
3‐Aza‐ und syn‐3,7‐Diazaoctabisvalen Synthesen, Röntgenstrukturanalysen, neue Heterocyclen
Authors: Trupp Björn , Fritz Hans , Prinzbach Horst , Irngartinger Hermann , Reifenstahl Uwe 
Published: July 2007

3‐Aza‐ and syn‐3,7‐Diazaoctabisvalene. ‐ Syntheses, X‐ray Structural Analyses, Novel HeterocyclesPreparatively useful routes for 3‐aza‐ and syn‐3,7‐diazaoctabisvalenes have been designed based on well available materials. Thus, 7‐cyano‐3‐azaoctabisvalene (4) becomes available in a six‐ (five‐) step synthesis from the valence tautomers 7‐cyanotropilidene ⇄ 7‐cyanonorcaradiene (7 ⇄ 8) (derived dioxides 9/10) in an overall yield of ca. 30%, syn‐3,7‐diazaoctabisvalene (5) in a three‐step synthesis from muco‐diazidotetrol 30a in ca. 25% overall yield. For 4 and 5 spectroscopic (e.g. 15N‐NMR resonances, 13C,13C coupling constants) and structural details (X‐ray analyses) are determined. 4 and 5 serve as starting materials for the construction of several novel heteropolycyclic skeletons (e.g. 46, 48, 50, 51, 52, 54).
N‐[α‐(o‐ and p‐Methoxyaryl)alkyl]benzotriazoles: Preparation and Use in Synthesis
Authors: Katritzky Alan R. , Lan Xiangfu , Lam Jamshed N. 
Published: July 2007

AbstractMethoxybenzenes and ‐naphthalenes are benzotriazolylmethylated in the para‐position or if this is blocked in an ortho‐ position. The methylene groups in the products are readily substituted by electrophiles via the lithiated derivatives. Displacement of the benzotriazole group can be effected by organometallic reagents or by electron‐rich benzoid compounds to afford a versatile method for the synthesis of substituted aryl ethers.
Improved Synthesis of Fluoromethanesulfonyl Chloride
Authors: Lange Ulla , Senning Alexander 
Published: July 2007

AbstractIntroduction of fluorine into 4‐chlorobenzyl chloromethyl sulfide (7) by crown‐ether‐assisted nucleophilic substitution furnishes 4‐chlorobenzyl fluoromethyl sulfide (5), a key intermediate for the preparation of fluoromethanesulfonyl chloride (1).
Synthese und Strukturen von metallhaltigen achtgliedrigen N — S — O‐Heterocyclen
Authors: Dembowski Udo , Noltemeyer Mathias , Gilje John W. , Roesky Herbert W. 
Published: July 2007

Synthesis and Structures of Metal‐Containing Eight‐Membered N — S — O HeterocyclesRacemic N‐alkylsulfinamides 1a, b react with aluminium, gallium, and indium alkyls 2a — d to form puckered eight‐membered NSO‐complexes [Me2AlN(CF3)2C6H3S(tBu)O]2 (3a), [Me2AlN‐(Ph)S(tBu)O]2 (3b), [Me2GaN(CF3)2C6H3S(tBu)O]2 (3c), [(Me3‐ SiCH2)2GaN(CF3)2C6H3S(tBu)O]2 (3d), [(Me3SiCH2)2InN(Ph)S‐ (tBu)O]2 (3e), and [(Me3SiCH2)2InN(CF3)2C6H3S(tBu)O]2 (3f). Compounds 3a, c, d crystallize in the triclinic space group P¯1. A comparision of the X‐ray structures of 3a, c, d reveals that the sulfur atoms in one molecule of 3d have either (R,R) or (S,S) configuration (Z = 2). In the case of less bulky ligands at the metal atoms (3a, c) both configurations at the sulfur atoms (R,S) are present in one molecule (Z = 1).
Eine einfache Synthese von 1,3‐Diphospha‐2,4‐disilabicyclo[1.1.0]butanen und Isomerisierung durch Silicium‐Inversion
Authors: DrieB Matthias , Pritzkow Hans , Reisgys Michael 
Published: July 2007

A Facile Synthesis of 1,3‐Diphospha‐2,4‐disilabicyclo[1.1.0]butanes and Isomerization by Silicon InversionDilithiation of the PH positions of the P2Si2 cyclobutanes 2a—h with n‐BuLi and treatment with tBuHgCl leads to the 1,3‐bis(tert‐butylmercurio) compounds 3a—h. According to NMR spectroscopy and X‐ray structural analysis the tert‐butylmercurio groups at phosphours occupy trans configuration. Photolysis of solutions of 3a—d and 3f, g in toluene yields the corresponding 1,3‐diphospha‐2,4‐disilabicyclo[1.1.0]butanes 1a—d and 1f, g. Interestingly, the dimercury compound 3e (R = mesityl and tert‐butoxy) is quite stable in visible light, probably due to intramolecular donor (tBuO) acceptor (Hg) stabilization. Starting from 3b, the light‐induced elimination of the tBuHg groups gives the expected exo,endo‐P2Si2‐bicyclo[1.1.0]butane 1b only as intermediate. The final product of the latter photolysis is the CMe3/CMe3‐exo,exo isomer 1b′. The formation of 1b′ from 1b is an irreversible silicon inversion process caused by unfavourable interaction of the endo substituents in 1b. In comparison, the exo,endo isomer of 1g (R = isityl and CMe3 at silicon) does not rearrange to the Me3C/Me3C‐exo,exo derivative 1g′ under similar photolysis conditions or when heated at 140°C for several days. The route to 1,3‐diphospha‐2,4‐disilabicyclo[1.1.0]butanes 1 described herein allows the synthesis of new derivatives which cannot be prepared from disilenes and white phosphorus.
Zur Kenntnis neuer 1,3,2,4‐Diphosphadisiletan‐ und Diorganodi(phosphino)silan‐Derivate
Authors: DrieB Matthias , Pritzkow Hans , Reisgys Michael 
Published: July 2007

Reaction of the bulkily substituted dichlorodiorganosilanes R1R2SiCl2 (R1 = Mesityl, R2 = Mesityl, tBu, OtBu, Xylyl, iBu) with LiPH2. dme in a 1 : 2 molar ratio in THF at ‐30°C leads to the new organo‐substituted 1,3,2,4‐diphosphadisiletanes 1a—e. Compounds 1c—e are isolated as mixtures of diastereomers. The crowded dichlorosilane Is(tBu)SiCl2 (Is = 2,4,6‐ triisopropylphenyl) reacts with LiPH2. dme above 10°C to yield the disubstituted products Is(tBu)Si(PH2)2 (2f) in 87% yield and only minor amounts of the corresponding four‐membered ring [Is(tBu)SiPH]2 (1f), detected by 31P‐ and 29Si‐NMR spectroscopy. Treatment of 2f with 2 equivalents of nBuLi in Et2O gives Is(tBu)Si(PHLi)2 (3f), which with Is(tBu)SiCl2 forms 1f. The reaction of difluorodiisitylsilane with LiPH2.dme in THF leads to different products, depending on the reaction temperature. At — 30°C Is2Si(PHLi)F (7g) is obtained as sole product, whereas at 28°C the air‐stable diphosphino‐substituted Is2Si(PH2)2 (2g) is formed. Elimination of LiF from 7g affords the tetraisityl‐substituted P2Si2‐cyclobutane 1g, and treatment with H2O and Me3SiCl leads to Is2Si(PH2)F (8g) and Is2Si(PHSiMe3)F (9g). The temperature‐dependent 1H‐NMR spectra of 1a — g exhibit two dynamic processes: hindered rotation of the aryl groups at silicon and inversion at phosphorus. — The solid state structures of 1a, 1b, 1g, and 2g are established by X‐ray crystallography. Reaction of 1a with 2 equivalents of M(CO)5.thf (M = Cr, W) yields the P,P′‐bis(pentacarbonylmetal) complexes 10a (M = Cr) and 11a (M = W). A single‐crystal X‐ray diffraction analysis of 10a is performed.Concerning New 1,3,2,4‐Diphosphadisiletanes and Diorganodi(phosphino)silane Derivatives
Kohlenstoffkettenlänge als Kontrolle bei der Stabilisierung von Propargylradikalen in Mangan(III)‐initiierten Reaktionen von 1‐Alken‐3‐inen. Ein einfacher Zugang zu langkettigen 4‐Acetoxy‐5‐alkinsäuren
Authors: Melikyan Gagik G. , Mkrtchyan Varsik M. , Badanyan Shaliko O. , Vostrowsky Otto , Bestmann Hans Jürgen 
Published: July 2007

Control of the Propargylic Radical Stabilization by Carbon‐Chain Length in Manganese(III)‐Mediated Reactions of 1‐Alken‐3‐ynes. – A Facile Synthetic Way to Long‐Chain 4‐Acetoxy‐5‐alkynoic AcidsBy investigation of reactions of 1‐alken‐3‐ynes RC  C – CH = CH2 4 with acetic acid/acetic anhydride, mediated by manganese(III) acetate, it has been found that the stabilization of propargylic radical adducts depends on the carbon‐chain length of R in 4. R = C8H17 is shown to be the “critical” chain length when ligand transfer reaction appears to be the only way of stabilization of intermediates, thus providing a facile one‐step access to long‐chain 4‐acetoxy‐5‐alkynoic acids. The dependence of the product ratios on the AcOH/Ac2O ratio has also been demonstrated.
Stereochemie der Ringöffnung von Aziridinonen (α‐Lactamen)
Authors: Quast Helmut , Leybach Holger 
Published: July 2007

Stereochemistry of Ring Opening of Aziridinones (α‐Lactams)The chiral, non‐racemic aziridinone (R)‐4 (e.e. 92%) reacts with magnesium halides to afford the α‐halo amides (S)‐3a (e.e. 88.8%), (S)‐3b (e.e. 89.0%), and (S)‐3c (e.e. 88.2%) in high yields. Acid‐catalysed hydrolysis of (R)‐4 in aqueous acetone yields 74% of the α‐hydroxy amide (S)‐3d (e.e. 88.0%). Methanolysis of (R)‐4 in [D4]methanol at 60°C followed the first‐order rate law with k = 1.53 ṁ 10–5 s–1 yielding quantitatively a 82:18 mixture of the α‐methoxy amide (S)‐3e (e.e. 89%) and the α‐amino ester (R)‐14 (e.e. 87%). The latter is obtained exclusively (e.e. 87%) when (R)‐4 reacts with sodium methoxide and methanol in ether while only the former is formed (e.e. 88.2%) by slow methanolysis in the presence of a catalytic amount of 4‐toluenesulfonic acid. The absolute configurations of the major enantiomers derived from (R)‐4 are based on the retention on a Chirasil‐L‐Val capillary gas chromatography column, CD spectra, and the comparison with authentic samples of (S)‐3a, obtained from (S)‐tert‐leucine [(S)‐1] and (S)‐3d. The results demonstrate that the N – C(3) bond of the aziridinone (R)‐4 is cleaved by nucleophiles with a high degree of stereospecificity and inversion of configuration. This stereochemical course is at variance with that inferred from the methanolysis of the similar aziridinone (R)‐7. – Treatment of (R)‐4 in [D4]methanol with one equivalent of 3‐chloroperbenzoic acid (15) containing 5% of 3‐chlorobenzoic acid (16) affords carbon monoxide and the racemic oxaziridine 18 in quantitative yield, which is also obtained from the imine 19 in a very fast reaction. The acid 16 effects slow decomposition of (R,S)‐4 into carbon monoxide and imine 19, probably by general acid catalysis. The stereochemical result obtained from (R)‐4 as well as the reaction conditions and differences in rate for formation and epoxidation of 19 suggest that in the peracid oxidation of an aziridinone the sequence of events consists of a rate‐limiting, acid‐catalysed decomposition into carbon monoxide and an imine, followed by very fast epoxidation of the latter. The previous mechanism, invoking as intermediates alleged aziridinone N‐oxides, e.g. 17, is not supported by the present study.