摘要:

AbstractThis review deals with the literature (covered up to August 1983), the characterization and the applications of Surface‐Modified Electrodes (SME). As a special class of SME's, the Enzyme‐Modified Electrode (EME) is introduced.Three types of modification procedures are distinguished;i.e.covalent modification, adsorption modification and polymer‐film modification. A further subdivision is made for catalysts attached to the electrode surface directly or via a bridge molecule. The characterization of SME's is mainly achieved via electrochemical techniques such as cyclic‐ and ac‐voltammetry. This theory is briefly described and illustrated with some of our own results.The name EME is used for a system in which the enzyme is immobilized at the electrode surface, such that direct electron transfer between electrode and enzyme becomes possible.The last part of this review deals with the applications of SME's and EME's. Examples are given of some already realized and of some possible app

ISSN:0165-0513    

DOI:10.1002/recl.19841030701

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

Abstractα‐ And β‐tosylated alkenylaromatic systems5c, dand9a‐care cyclized to6c, dand10a‐cin FSO3H‐containing SO2in synthetically useful processes. Dibal‐H treatment of α‐substituted6c, dbrings about rapid, high‐yield detosylation to7c, d; the β‐tosylated isomers10a‐cgive, with Dibal‐H, after 18 h in refluxing toluene, mainly unreacted sulfones together with minor amounts of sulfides11a‐c. Ring‐disrupted congeners15a‐dand18a‐cbehave likewise, with α–tosylated15a‐dbeing rapidly detosylated by Dibal‐H to16a‐dand their β‐substituted isomers undergoing low‐yield reductions to sulfides19a‐c. Dibal‐H mediated detosy

ISSN:0165-0513    

DOI:10.1002/recl.19841030702

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractDeprotonation of 2‐(diethylamino)‐5‐phenyl‐3H‐azepine (1) with different base systems yields an anionic species, which, on treatment with appropriate electrophiles, gives the 3‐substituted deri

ISSN:0165-0513    

DOI:10.1002/recl.19841030703

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractOzonolysis of olefinsIa‐ccontaining a cyclopropylidene group, does not follow the classicalCriegeemechanism but gives the anomalous productsIIa‐c, IIIa‐c,IVa‐candVa‐c, as outlined in Scheme 2. None of these oxidation products contains the cyclopropyl ring any more. It is suggested that primary ozonides containing a cyclopropyl moiety, undergo already at low temperature simultaneous 0–0 homolysis and small‐ring fission, thus generating the key intermediate 1, 6‐biradicalX(Scheme 4). This is at the same time a peroxy and a carbon radical, which upon combination –in casucyclisation – gives the six‐membered peroxa‐ketoneII. Apart from combination, biradicalXcan also undergo intramolecular disproportionation to the unsaturated ketoneXIX(Scheme 8) containing a terminal hydroperoxy function. This product does not accumulate as such, but is further oxidised to the epoxideVa‐cwith simultaneous formation of the five‐membered cyclic 1, 3‐oxa‐ketoneIIIa‐c(cfScheme 8). The least oxygen‐rich reaction product is the cyclobutanoneIV, for which zwitter ionXIVor its ring‐expanded isomerXV(Scheme 6) is a likely precursor.Interception of the first zwitter ion by methanol, followed by loss of oxygen, explains the formation of glycol derivativesVI(Scheme 6). Direct attack ofXVIII(Scheme 8) on starting material, provides an other route towards the cyclobutanoneIV, which is suppressed in the presence o

ISSN:0165-0513    

DOI:10.1002/recl.19841030704

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractReactions of octachlorocyclotetraphosphazene (NPCl2)4with methyl lithium and isopropylalcohol or alkyl iodides afford hydrido‐phosphazenes and bi(cyclotetraphosphazenes). A reaction mechanism, based on an initial metal‐halogen exchange process, is propo

ISSN:0165-0513    

DOI:10.1002/recl.19841030705

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

Abstract1, 6‐Anhydro‐β‐D‐mannopyranose was converted in three steps into 1, 6‐anhydro‐3‐0‐(4‐methoxybenzoyl)‐4‐0‐allyl‐β‐D‐mannopyranose in high overall yield. Treatment of the latter with trifluoromethanesulphonic anhydride, followed by direct displacement at 20°c of the triflate ester with lithium azide afforded almost quantitatively 1, 6‐anhydro‐2‐azido‐2‐deoxy‐3‐0

ISSN:0165-0513    

DOI:10.1002/recl.19841030706

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY