摘要:

AbstractThe recent exciting developments concerning the structure and function of the CuAsite in cytochromecoxidase (COX) and nitrous oxide reductase are reviewed. The XRD structures of a mitochondrial and a bacterial COX have been reported in 1995. In COX, the CuAcentre is located in subunit II and is involved in electron transfer from a cytochromecdonor to the oxygen binding centre of the protein. The structural studies on the enzyme have revealed the coordination geometries of the many metal centres of COX, including the CuAsite. A combination of spectroscopic and mutagenesis studies on the CuAcentre led to the correct prediction of the structure of this unique copper centre. The construction of a CuAsite in type 1 blue copper proteins is briefly discussed.

ISSN:0165-0513    

DOI:10.1002/recl.19961150702

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractHydroxyalkylation of phenol with glyoxylic acid, catalyzed by AlIII, results, under neutral aqueous conditions, inortho‐rich mixtures of hydroxymandelic acids.Para‐rich mixtures of hydroxymandelic acids are obtained by ZnIIcatalysis under slightly alkaline conditions. A new separation method of these mixtures into the pure alkali salts of 2‐ and 4‐hydroxymandelic acid is presented. Formation of a complex between the alkali ion and three co‐operating oxygen atoms of 2‐hydroxymandelate explains the excellent solubility of theorthoisomer in acetone, enabling extraction of this isomer selectively from mixtures of alkali salts of 2‐ and 4‐hydro

ISSN:0165-0513    

DOI:10.1002/recl.19961150703

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA series of receptors functionalized with chiral aza‐crown ether rings was synthesized. These compounds were studied as enantiopure catalysts for the addition of benzenethiols to cyclohex‐2‐en‐1‐one. Binding of 4‐hydroxybenzenethiol in these molecules allows for the orientation of the thiol with respect to an asymmetric catalytic site. This orientation was, however, found to be counterproductive for enantioselectiv

ISSN:0165-0513    

DOI:10.1002/recl.19961150704

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe synthesis of several calix[4]arenes functionalized with uracil or diaminotriazine moieties is described. The association between these complementary calix[4]arenes is strongly influenced by processes related to the position and directionality of the hydrogen‐bonding moieties. In the case of bis(uracil)calix[4]arene (4), self‐association is observed (K= 3.4 · 103M−1in CDCl3) whereas, in the case of bis(diamidotriazine)calix[4]arene (16), it was concluded from1H‐NMR studies that intermolecular association is hampered by the formation of intramolecular hydrogen bonds. Due to the divergent orientation of the hydrogen‐bonding groups of bis(diaminotriazine)calix[4]arene (15b), it forms hydrogen‐bonded strands through interaction with 5‐ethyl‐5‐phenylbarbituric acid (17), resulting in the formation of a

ISSN:0165-0513    

DOI:10.1002/recl.19961150705

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractReaction of 5,12‐dialkylthioquinanthrenediinium bis‐salts1with primary alkylamines led to the synthesis of 1‐alkyl‐4‐(alkylamino)quinolinium‐3‐thiolates (2). Their structures were proved by X‐ray examination,1H‐NMR spectroscopy and by transformation to 1‐alkyl‐4‐(alkylamino)‐3‐(alky

ISSN:0165-0513    

DOI:10.1002/recl.19961150706

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractTreatment of 2,3,5,6‐tetraphenylpyrazine (1) with sodium in tetrahydrofuran effected the formation of monomeric dianion2. The chemical behaviour of this new disodium adduct was characterized by a variety of reagents. Generally, the protonation (water), alkylation (methyl iodide and benzyl chloride), and acylation (methyl and ethyl chloroformate) products were 1,2‐dihydrotetraphenyldiazine derivatives. An annulation of the pyrazine ring system was accomplished by treating the dianion with polymethylene chlorides, Cl(CH2)nCl,n= 2, 3

ISSN:0165-0513    

DOI:10.1002/recl.19961150707

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150709

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150711

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150714

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19961150701

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY