摘要:

Synthesis and Structure of the Polycyclohexaphosphines P6(C5Me5)4and P6(C5Me5)2The cyclotriphosphine (PC5Me5)3(1) decomposes in boiling benzene to give the bicyclo[3.1.0]hexaphosphine P6(C5Me5)4(2) which yields the tricyclo[3.1.0.02.6] hexaphosphine P6(C5Me5)2(3) in boiling xylene. The structures of2and3have been determined by31P‐,13C‐, and1H‐NMR spectroscopy and by X‐ray crystallography.3represents the first member of a new class of polyphosphines. The specific thermolysis of1and2under comparatively mild conditions is based on the easy homolytic cleavage of P — C5Me5bonds in these

ISSN:0009-2940    

DOI:10.1002/cber.19911240112

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractButyltin triisopropoxide reacts with benzoyl(thiobenzoyl)methane (LH) to yield BuSn(S)L and an organic sulfide2instead of the expected BuSnL3. The use of other butyltin(IV) starting materials invariably leads to the same products. From an X‐ray structure determination the tin sulfido complex is found to be a centrosymmetric dimer, [BuSn(S)L]2(1) with a planar four‐membered Sn2S2ring containing pentacoordinated tin at

ISSN:0009-2940    

DOI:10.1002/cber.19911240113

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractHg[C(COF) = SF2= O]2is prepared by the reaction of FCO  CH = SF2= O with HgF2. This compound represents the third known example of an alkylidenesulfur difluoride oxide. Its molecular structure is the same as that of the most abundant of the three isomers of FCO‐CH = SF2= O. This is assumed to be the result of weak intramolecular Hg… O contacts. With the exception of the fluorine atoms bound to sulfur, all atoms lie approximately in one

ISSN:0009-2940    

DOI:10.1002/cber.19911240114

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

Heterocycles as Ligands, X1). — 2,2′,5,5′‐Tetra‐tert‐butyl‐1,1′‐diazaferrocene – Stabilization of the Diheterometallocene Structure by Steric ShieldingStable 2,2′,5,5′‐tetra‐tert‐butyl‐1,1′‐diazaferrocene (3) is obtained by the reaction of the corresponding lithiopyrrole with FeCl2. The X‐ray analysis reveals a distorted sandwich structure influenced by repulsive interactions presumably both between the nitrogen atoms

ISSN:0009-2940    

DOI:10.1002/cber.19911240115

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

On the Knowledge of the “Silanephosphimine” (Phosphasilaethene)tBu2Si = PSitBu31,2)The lithium phosphide3acts as a source for the “silanephosphimine”2. Thermolysis of3at 80–120°C in the presence of Li⊕(tBu3Si⊖PH), CH2= CMe2, or CH2= CHCH = CH2leads to products4, 7or8, whose formation is interpretable by the reaction of the reactants with intermed

ISSN:0009-2940    

DOI:10.1002/cber.19911240116

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractPd[P(tBu)3]2reacts photochemically with an excess of phenol inn‐hexane to give the dinuclear complex [{P(tBu)2H}2Pd2{μ‐P(tBu)2}(μ‐η2:η2‐C6H5O)]  3 C6H5OH (1); X‐ray crystallography shows a linear chain of three phenol molecules hydrogenbonded to the phenoxide ligand which is η4‐coordinated to the Pd2framework. The π coordination of the phenoxide ring is retained in solution, as evidenced by

ISSN:0009-2940    

DOI:10.1002/cber.19911240117

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

Asteranes, XXII1). — Synthesis of a Double Tetraasterane: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosane1,4,5,8‐Tetrahydronaphthalene‐2,3‐dicarboxylic anhydride (9) is dimerized by UV light in dioxane yielding four isomeric [2 + 2] adducts whose methyl ester derivatives are elucidated spectroscopically. The structures of the major products14and16have been confirmed by X‐ray structure analysis. Degradation of the carboxylic groups of14afforded the title

ISSN:0009-2940    

DOI:10.1002/cber.19911240118

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractOn heating at 100°C, 1,2,3,4‐tetrahydro‐6,7‐dialkoxy‐1‐[(acylamidino)methylene]isoquinolines (5) are transformed into 4‐substituted 6,7‐dihydro‐9,10‐dialkoxy‐2H‐pyrimido[6,1‐α]isoquinoline‐2‐imines (6), while at 140°C they undergo a novel prototropic rearrangement via6to give 4‐amino‐6‐(4,5‐dialkoxy‐2‐vinylphenyl)‐2‐phenylpyrimidines (7). The struc

ISSN:0009-2940    

DOI:10.1002/cber.19911240119

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe 6‐(trimethylsilyl)methyl‐substituted 1,2‐oxazine1can smoothly be deprotonated withn‐butyllithium at C‐4 to give a lithiated species which reacts with a variety of electrophiles to provide the new 1,2‐oxazines5–16in good yields. Besides the preparative aspect of these transformations, the high stereoselectivity of many reactions is also interesting from a mechanistic point of view. By deprotonation of the 4‐deuterated compound5ait has been proven thatn‐butyllithium removes exclusively the proton (or deuteron)cisto the 6‐CH2SiMe3group. Also, in most cases the reaction of lithiated1with electrophiles occurs withoverall retention of configurationto afford preferentiallycis‐1,2‐oxazines (seriesa). A mechanistic proposal for this highly stereoselective deprotonation process, which seems to be governed by the 1,2‐oxazine oxygen, is discussed including a comparison with a recently reported ab initio calculation dealing with oxime ethers. Similar deprotonation/substitution reactions are described for 1,2‐oxazines14, 2, 3, and4. Possibly due to a differing carbanion structure a deviating behavior is observed in some cases. Several acidinduced and reductive ring‐opening reactions of1, 6a, 8a, and14ademonstrate the potential of 4‐substituted 1,2‐oxazines for the stereoselective synthesi

ISSN:0009-2940    

DOI:10.1002/cber.19911240120

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

Electrochemical and Spectroscopic Characterization ofN,N′‐Dialkylquinoxalinium Redox SystemsThe outstanding position of the 1,4‐isomer, quinoxaline, among the diazanaphthalenes is confirmed by comparing LUMO energies from HMO perturbation calculations. Diquaternary salts [(R+)2(quin)](X−)2, R = Me, Et; quin = quinoxaline, 2,3‐ and 6,7‐dimethyl‐ and 2,3,6,7‐tetramethylquinoxaline, X−= BF4‐or SbCl6‐(4a – g), were isolated and characterized as compounds which are sensitive to reduction and hydrolysis. Cyclic voltammetry of the two‐step redox systems of the Weitz type showed two reversible one‐electron reductions with an extraordinarily stable radical cation intermediate (lgKc12). The redox potentials are less negative than those of the 4,4′‐bipyridinium systems but also less positive in comparison to the values ofN,N′‐dialkylphenazinium compounds. The radical cation intermediates which include a TCNQ−salt cannot only be characterized by ESR, but also by absorption spectroscopy in c

ISSN:0009-2940    

DOI:10.1002/cber.19911240121

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY