摘要:

AbstractSynthetic procedures have been developed for the preparation of ligands bearing two to six pendent, unsubstituted or substituted 2, 2′‐bipyridine groups attached to acyclic (tripode, tetrapode) and macrocyclic (triazanonade‐cane, cyclam, hexacyclen, bis(bipyrido)hexaazamacrocycle) polyamines. Ligands1‐5have been obtained in high yield by condensation of 6‐(bromomethyl)‐2, 2′‐bipyridine (9b) with the corresponding amines in the presence of NaOH, H2O, and MeOH. Ligands6‐8have been prepared in good yield by condensation of9bor the di‐ or tetrasubstituted mono (bromomethyl) bipyridine10b or 11b, respectively, with the corresponding amines in the presence of Na2CO3and MeCN. Ligand1forms hemi‐cage complexes with RuII, FeI, CrII, and CrIIIcations and trinuclear complexes with [RuCl2(bpy)2] and [ReCl(CO)5]. Tetrapode2and hexapode4gave tetranuclear and dinuclear complexes, respectively, by reaction with Fe11 salts. These complexes possess a variety of interesting physical an

ISSN:0018-019X    

DOI:10.1002/hlca.19900730502

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe metastable ions of Fe+complexes of aldimines R1NCHR2exhibit a unique behaviour in that sequential loss of olefin/H2follows two distinct pathways: one corresponds to the familiar pattern of double remote functionalization, involving either alkyl chain R1and R2. In addition, based on labeling studies, evidence is presented demonstrating that the consecutive elimination of C2H4/H2from the Fe+complex of C6H13NCHC3H7involves exclusively the C6H13part of the substrate. These and other Fe+‐mediated CH/CC bond activations of aldimines are controlled by chain‐length effects, reflecting the preferential formation of metallacyclic intermediates of particular

ISSN:0018-019X    

DOI:10.1002/hlca.19900730503

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractHexamethylbenzene and its derivatives undergo very clean regioselective dinitration to dinitroprehnitene (1, 2, 3, 4‐tetramethyl‐5, 6‐dinitrobenzene) with excess of nitronium tetrafluoroborate in dry CH2C12solution. The mechanism of this unexpected new nitration is also disc

ISSN:0018-019X    

DOI:10.1002/hlca.19900730504

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe recently developed general principle of ion‐selective optode membranes, based on conventional ionophores, was employed to design a new approach to the determination of enantiomeric excess. Highly lipophilic chiral crown derivatives, exhibiting a high selectivity for a chiral ammonium guest cation, are combined with a H+‐selective chromoionophore in a plasticized PVC membrane. The enantiomer recognition process is translated by this sensor with an optical transduction into a signal easily measured by a conventional spectrophotometer, and enantiomeric excess can be determined without the need for polarized light. Characteristics and a theoretical description of these new optode membranes are gi

ISSN:0018-019X    

DOI:10.1002/hlca.19900730505

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractPentacyclo[6. 4. 02, 4. 03, 10. 07, 9]dodeca‐5, 11‐diene(4) is proposed as new potential precursor of the truncated tetrahedrane1. The synthesis of several new pentacyclo[5. 4. 0. 02, 4. 03, 9. 06, 8] undec‐10‐ene (4, 5‐homosnoutene) derivatives including homosnouten‐5‐one(10), 5‐methylidenehomosnoutene(19a) as well as homosnoutene‐5‐carb‐aldehyde(17b) and their reactions directed toward ring enlargement to the skeleton of4are reported. Although all the homosnoutenes resisted ring expansions, several unexpected new polycyclic systems were obtained. Any intermediate developing a cationic center at C(5) of the skeleton of 10 rearranged with release of strain and opening of one or both three‐membered rings to give compounds such as22and23. The aminomethyl derivatives 13a and 13b, upon diazotation, underwent a remarkable fragmentation to give 10 and homosnouten‐5‐o1(20), respectively. The 5‐(dibromomethyl) homosnouten‐5‐o1(14), upon treatement witht‐BuLi, rearranged to the pentacyclic ether15, while the carbine11b, generated by the thermal or photochemical decomposition of the tosylhydrazone salt of17c, solely gave19aby C, H insertion. The 1, 1‐dicyclopropylethene unit in19cwas excited selectively upon irradiation, but the products26and27of this photochemical rearrangement were derived only from n‐particip

ISSN:0018-019X    

DOI:10.1002/hlca.19900730506

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractCompound (Z)‐8ahas been found to display interesting antiinflammatory activity. In order to prepare derivatives with a wide variety of substituents in the aromatic part of the molecule, a new synthesis of the key intermediates9a‐gwas developed starting from thiophene‐3‐carboxylic acid (11) and substituted benzyl bromides. The conversion of9a‐gto10a‐gfollows a known procedure. Ketones10a‐g, on reaction with alkyl (dialkoxy‐phosphoryl)acetate, followed by isomer separation and alkaline ester hydrolysis, yielded the desired derivatives (Z)‐8a‐gand (E)‐8a‐g. The biologically most interesting compound (Z)‐8ais currently u

ISSN:0018-019X    

DOI:10.1002/hlca.19900730507

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

A Further, Now Successful Search for 3′‐Epilutein in PlantsThe 3′‐epilutein, an extremely rare carotenoid, found till now in only one plant, was detected in anthers of flowers of several roses and in those of

ISSN:0018-019X    

DOI:10.1002/hlca.19900730508

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

‘tert‐Amino Effect’ on Acidic Treatment of (Pyrrolidin‐l‐yl)azadienesThe behaviour of 4‐morpholino‐ and 4‐(pyrrolidin‐l‐yl)‐2‐aza‐1. 3‐diene‐l, l‐dicarbonitriles3, and4and10, respectively, in acidic medium is described. The former gives with HBr/AcOH 3‐bromopyrazine‐2‐carbonitrile 6. On the other hand, pyrrolidin‐1‐yl derivatives4and10furnish, by a [1, 5]‐H shift, pyrrolo[l

ISSN:0018-019X    

DOI:10.1002/hlca.19900730509

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe infrared quasi‐resonance stepwise‐multiphoton‐dissociation spectra of the molecular ions of 1‐bromo‐propene, 2‐bromopropene, 3‐bromopropene, and bromocyclopropane have been obtained at selected wavelengths between 9. 2 and 10. 7 μm in aFourier‐transform mass spectrometer. The resulting spectra and the photo fragmentation kinetics suggest that these molecular ions retain their identity upon ionization, and can, thus, provide fingerprint spectral identificati

ISSN:0018-019X    

DOI:10.1002/hlca.19900730510

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe mononuclear η1‐dioxygen complex [Co(CN)5O2]3−(A) decomposes in aqueous solution to the hydroxo‐complex [Co(CN)5OH]3−(B) and the hydroperoxo complex [Co(CN)5CoO2N]3(C). The mechanism involves partial dissociation of A to give [Co(CN)5]3−(E) which binds with unreacted A to give the η1:η1‐peroxo complex [(CN)5Co02Co(CN)5]6−(F) which is hydrolysed toBandC. The mechanism is supported by the effects of pH, dioxygen concentration, and ionic strength on the rate of decomposition, and by the trapping of oxidation products ofEandF. Complex A reacts readily with reducing agents to give directly the hydro

ISSN:0018-019X    

DOI:10.1002/hlca.19900730511

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY