摘要:

AbstractThe synthesis of two sets of analogues of 2‐5A trimer containing 9‐(3‐fluoro‐3‐deoxy‐β‐D‐xylo‐furanosyl)adenine (AF) or 3′‐fluoro‐3′‐deoxyadenosine (AF) at different positions of the chain is described, along with the preparation of the corresponding 5′‐monophosphates and 5′‐diphosphorylated (core) trimers. The ability of eachriboandxyloisomeric pair of fluorodeoxy analogues of 2‐5A (i) to compete with p3(A2′p)3A3′[32P]pC3′p for binding to RNase L in L929cell extracts, and (ii) to activate the partially purified RNase L from L929cell extracts to hydrolyze poly(U)[3H], was compared to that of the related 3′‐deoxy analogue [Torrenceet al., J. Biol. Chem.263, 1131 (1988)] and the parent trimer, p3A3, using radiobinding and RNase L‐(2′,5′)pentaadenylate(core)‐agarose assays, respectively. Evidence is presented to show that the stereochemistry of the trimers plays an important role, specifically in the second process. The most striking observation is that, compared to 2‐5A, p3A(AF)A was found to be nine times more effective an activator of RNa

ISSN:0165-0513    

DOI:10.1002/recl.19951140202

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe synthesis of thiophenes starting from allenyl sulfones, via intermediate formation of α,β‐unsaturated sulfines, is described. The allenyl sulfones were synthesized by a [2,3]‐sigmatropic rearrangement of appropriately substituted prop‐2‐ynyl sulfinates. Treatment of the allenyl sulfones withn‐butyllithium and chlorotrimethylsilane gave α‐silylated allenyl sulfones in almost quantitative yield, which, on heteroconjugate addition of organolithium reagents, gave the desired α‐silyl carbanions. These reacted with sulfur dioxide to give the α,β‐unsaturated sulfines, which underwentin‐siturearrangement to 2‐sulfonylthiophenes. The yield of the thiophenes depends on the organolithium reagents used. The use of exocyclic allenyl sulfones was more troublesome, and a thiophene was obta

ISSN:0165-0513    

DOI:10.1002/recl.19951140203

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractCopper has been determined by a modified dual‐wavelength spectrophotometric (DWS) method, using the reaction of CuIIwith eriochrome blue black R (EBBR) at pH 12, which is sensitive and selective in the presence of both pentadecyltrimethylammonium bromide (PTMAB) and ascorbic acid. The modified DWS can completely eliminate the effect of excess EBBR in its CuIIsolution and give the real absorbance of the produced chelate of CuIIwith EBBR, with increased analytical sensitivity and decreased error. The composition of the complex of CuIIwith EBBR can be determined easily and accuratively. Beer's law is obeyed over the concentration range of 0‐1.60 mg Cu per 1 and the true molar absorbance of chelate Cu(EBBR)2at 550 nm has been computed as 1.80 · 104· mol−1· cm−1. The detection limit of Cu is 0.04 mg. This method has been applied for the determination of trace amounts of copper in waste water with satisfacto

ISSN:0165-0513    

DOI:10.1002/recl.19951140204

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe design and synthesis of two novel chiral receptors derived from diphenylglycoluril are described. The chirality in these molecules is due to the unsymmetrical positioning of amino functions in the crown ether rings with respect to the diphenylglycoluril subunit.

ISSN:0165-0513    

DOI:10.1002/recl.19951140205

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractMethylpalladium complexes containing phosphine‐phosphinite bidentate ligands1‐3undergo stepwise insertions of carbon monoxide and norbornadiene. The31P NMR spectra prove that a true migration pathway is the mechanism for this react

ISSN:0165-0513    

DOI:10.1002/recl.19951140206

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19951140207

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19951140209

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19951140210

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19951140201

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY