摘要:

AbstractOrganozinc reagents FG‐(CH2)nZnX containing electrophilic centers (FG) upon conversion to their corresponding zincates (FG‐(CH2)nZnMe2Li) and in the presence of 5–8 mol % MeCu(CN)Li, undergo 1,4‐additions to cyclic conjugated enones. The intermediate zinc enolates can be trapped with aldehydes to afford products of three‐component

ISSN:0009-4536    

DOI:10.1002/jccs.199700001

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractVariously functionalized 1,5‐ and 1,7‐azulenequinones were easily derived in one‐pot in 30‐50% yield from the bromine‐oxidation of 2‐methoxyazulene and 2‐methyl derivatives of 1‐cyano‐, 1‐methoxycarbonyl‐ and its 7‐isopropyl derivatives, while 1‐methoxycarbonylazulene afforded several unstable products from which we could not isolate any azulenequinones. 1‐Acetylazulene afforded 3‐bromo‐1,5‐ and ‐1,7‐azulenequinones via side‐chain brominated intermediates in high yield. 1,3‐Dichloroazulene afforded a mixture of 3‐chloro‐1,5‐ and −1,7‐azulenequinones, while 1‐fluoro‐ and 1,3‐diiodoazulene gave a mixture of 3‐bromoazulenequinones. Analogous oxidation of 1,3‐difluoroazulene produced 3‐fluoroazulenequinones, but we could not isolate them due to its instability. Hydroxy group of 2‐(3‐hydr

ISSN:0009-4536    

DOI:10.1002/jccs.199700002

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA membrane electrode selective to hexadecylpyridinium bromide was used to study the micellization of the surfactant in the presence of varying concentrations of crown ethers 15‐crown‐5, dicyclohexyl‐18‐crown‐6 and dicyclohexyl‐24‐crown‐8 at 27°C. The critical micelle concentration of surfactant was largely influenced by the crown ethers used, indicating their participation in the structure of the resulting micelle. The degree of attachment of crown ethers to the surfactant in the micellar structure was found to be 1. An estimation of the Kffor the 1:1 surfactant‐crown interaction in the micellar region is reported. The degree of counter ion dissociation was found to increase with the crown ether concentration, and with the nature of macrocyclic ligands in the order 15‐crown‐5

ISSN:0009-4536    

DOI:10.1002/jccs.199700003

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA simple but innovated calibration procedure for the measurements of volatile organic compounds in the atmosphere is introduced via the use of CCI2FCCIF2(CFC‐113) long‐term global data set as an illustration. Non‐linear response for the electron capture detector toward CFC‐113 was carefully calibrated within and beyond the measurement working range. Our measurement results, after correction for non‐linearity, are in excellent agreement with those of the ALE/GAGE monitoring program, suggesting our calibration method along with its results are experimentally sound and well executed.Our global measurements show that, after years of rapid growth of CFC‐113 in the atmosphere, its concentration had been leveling‐off and even started to de

ISSN:0009-4536    

DOI:10.1002/jccs.199700004

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA series of “push‐pull” porphyrins with 4‐nitrophenyl and 4‐aminophenyl substituents were synthesized and separated by flash column chromatographic techniques. They were fully characterized by elemental analysis, FAB‐MS, FTIR, UV‐visible, and1H NMR spectroscopies. The unsymmetrical π‐electron distribution of the porphyrins caused by the donor (amino) and acceptor (nitro) substituents were investigated by1H NMR technique. The pyrrole‐H resonance positions can be correlated to the Hammett σ constants of the substituents. Although with strong donor and acceptor substituents, UV‐visible spectra show the push‐pull porphyrins have rather weak solvatochromism and hence limited intramolecular ch

ISSN:0009-4536    

DOI:10.1002/jccs.199700005

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractKnown to be a facile irontricarbonyl transfer reagent, (η2‐cis‐C8H14)2Fe(CO)31 transfers its Fe(CO)3unit to a variety of ligands at low temperature. Stirring a THF mixture of 1 and PhC=CPh under N2(g) at −60 °C for 1 h then at room temperature overnight provides mainly a flyover‐bridge product [‐CPh=CPhC(0)‐CPh=CPh‐]Fe2(CO)62 with the organic bridge on diiron core in a complicated μ‐(1,2,5‐η3:1,4,5‐η3) fashion. The keto fragment in 2 comes presumably from the decomposition of 1 that liberates CO. However, stirring a THF mixture of 1 and PhC=CPh under CO(g) at −60 °C for 3 h then at room temperature overnight results in [‐C(0)CPh=CPhC(0)‐]Fe(CO)43, a compound not isolated in the earlier thermal or photochemical reactions of PhC=CPh with ironcarbonyl. The X‐ray structure determinations for

ISSN:0009-4536    

DOI:10.1002/jccs.199700006

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractReaction of MoCo(CO)5(PPh3)2(η5‐C5H5) (1a) with trimethylsilylacetylene in tetrahydrofuran at 58° C yielded two acetylene bridged heterobimetallic compounds, MoCo(CO)4(PPh3){μ‐HCCSiMe3}(η5‐C5H5) (4) and MoCo (CO)5{μ‐HCCSiMe3}(η5‐C5H5)(5). (4) was characterized by mass, infrared,1H,13C and31P NMR spectra. The X‐ray crystal structure of (4) was determined:triclinic, P‐1, a=8.821(1) Å, b=11.315(3) Å, c=17.029(2) Å, α=70.73(1)°, β=78 .72(1)°, γ=86.10(2)°,V =1573.4(6) Å3, Z=2, R = 3.92%,Rw= 6.06% for 4285 (F>4σ (F)) observed reflections. The core of this molecule is a quasi‐tetrahedron containing Mo, Co and two carbons of acetylene. The triphenylphosphine ligand is attached to

ISSN:0009-4536    

DOI:10.1002/jccs.199700007

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractBromination of binor‐S resulted in a mixture of products containing several pairs of isomers. Three major processes were found to be involved in the reaction mechanism, i.e., bromination, hydrobromination, and dehydrobromination. The structures of nine compounds derived from dibromide 6 were identified by spectroscopic methods. Yields between isomers were rationalized by comparison of their relative strain energies calculated by force field model (MM2). The crystal structures of a tribromide (9) and a pentabromide (15) were solved by X‐ray diffraction analyses. Their crystal packing patterns indicated the existence of attractive interactions among the bromine at

ISSN:0009-4536    

DOI:10.1002/jccs.199700008

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA total synthesis of (±)‐patriscabrol (1) and (±)‐boschnialactone (2) is described. The cyclopentapyranone skeleton is assembled by means of Baeyer‐Villiger oxidation of

ISSN:0009-4536    

DOI:10.1002/jccs.199700009

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractMethyl ketone is prepared by a sonochemical Barbier reaction of methyl iodide, magnesium powder and aldehyde in Benzene/THF (9/1) solvent in a commercial ultrasonic cleaning bath (39 kHz), followed by the addition of N‐chlorosuccinimide (NCS) as an oxidizing agen

ISSN:0009-4536    

DOI:10.1002/jccs.199700010

出版商:WILEY‐VCH Verlag    

年代:1997

数据来源: WILEY