The Synthesis of Polyfluoroalkylbiphenyl

Polyfluoroalkylated biphenyl was obtained from reaction of benzene with R_FI/Na_2S_2O_4 using cetyltrimethylammonium bromide (CTAB) as PTC followed by dehydrogenation with DDQ in 38-43% yield.     

The Synthesis of Glycoglycerolipids

A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained.     

The Division of Analytical Chemistry of The Federation of European Chemical Societies

ＦＥＣＳ ,ｔｈｅＦｅｄｅｒａｔｉｏｎｏｆＥｕｒｏｐｅａｎＣｈｅｍｉｃａｌＳｏｃｉ ｅｔｉｅｓ,ｃｏｍｐｒｉｓｅｓａｎｕｍｂｅｒｏｆＤｉｖｉｓｉｏｎｓａｎｄＷｏｒｋｉｎｇＰａｒ ｔｉｅｓｓｐｅｃｉａｌｉｚｉｎｇｉｎｃｅｒｔａｉｎｆｉｅｌｄｓｓｕｃｈａｓＦｏｏｄＣｈｅｍ ｉｓｔｒｙ ,ＥｌｅｃｔｒｏｃｈｅｍｉｓｔｒｙｏｒＣｈｅｍｉｃａｌＥｄｕｃａｔｉｏｎ .ＡｍｏｎｇｔｈｅｍｔｈｅＤｉｖｉｓｉｏｎｏｆＡｎａｌｙｔｉｃａｌＣｈｅｍｉｓｔｒｙ ,ＤＡＣ ,ｉｓｏｎｅｏｆｔｈｅｌａｒｇｅｓｔｗｉｔｈｒｅｓｐｅｃｔｔｏ…     

The Preparation of β-Hydroxysulfoxides

. Oxidation of β-hydroxy thioethers with MnO₂-aqu. 35%/HCl in methanol gives β-hydroxy sulfoxides in high yields.     

Studies on The Adsorption Capacity for Bilirubin of The Adsorbent Chitosan-β-Cyclodextrin

Bilirubin is a metabolite of heme from hemoglobin in the blood. Disorders in its successive metabolism or excretion may cause the accumulation of the unconjugated bilirubin in blood of the patients who suffer from hyperbilirubinemia. The accumulation of bilirubin can cause serious tissue damage1,2. Hyperbilirubinemia may be treated by the removal of bilirubin from body. The ways for its removal include phototherapy, orally administered sorbents3 and adsorbents for hemoperfusion. Successful he…     

Quasiliving Carbocationic Polymerization. II. The Discovery: The α-Methylstyrene System

A detailed analysis of elementary reactions of carbocationic polymerization culminated in the prediction and subsequent experimental demonstration of quasiliving polymerization. Quasiliving polymers are formed in a system provided that the process of chain termination and chain transfer to monomer are absent or reversible, i.e., the propagating ability of the chain end is maintained throughout the experiment, and the molecular weight increases in proportion to the cumulative amount of monomer added. The chain end can be active (carbocation) or dormant (reactivable polymeric olefin or cation source). Chain transfer is suppressed by keeping the monomer concentration low. Quasiliving polymerizations are maintained by continuous slow feeding of dilute monomer to a charge containing the initiating or propagating species (quasiliving polymerization technique). A comprehensive kinetic scheme has been developed that describes quasiliving polymerization in quantitative terms. Quasiliving polymerization was demonstrated experimentally in the “H₂O”/BCl₃/α-methylstyrene and cumyl chloride/BCl₃/α-methylstyrene systems. M _n versus monomer input plots are linear over wide ranges, indicating quasiliving conditions, and poly(α-methylstyrenes) with M _n > 2 × 10⁵ have been obtained, Molecular weight distributions were found progressively to narrow and dispersion ratios M _w/M _n to decrease.     

The “bringer” strategy

Random mutagenesis constitutes a keystone in many strategies of directed evolution of biocatalysts and is often done by error-prone polymerase chain reaction (epPCR). Traditionally, the epPCR-generated DNA fragments are then subcloned into an expression vector to obtain a mutant library, which in turn is transformed into a suited host and screened for mutants that display the desired property. However, the vast majority of epPCR-generated fragments generally are lost during the subcloning step, making it the bottleneck in the mutant library construction procedure. Here we report a rapid and convenient strategy based on the epPCR amplification of a ring-closed expression plasmid that contains the gene of interest; after a DpnI digest the product of the epPCR reaction constitutes the mutant library and can be used directly for screening procedures. Primers binding to the beta-lactamase gene were chosen to allow application of the strategy to as broad a range of target plasmids as possible. The functionality of this approach was demonstrated by mutating the alpha-peptide coding region of the lacZ gene.     

The Chemistry of Hainanensine Derivatives

Hainanensine(1) and its analog 6 were obtained through intramolecular regiospecific cycliza-tion. Reduction of 6 under different conditions gave 7～12. The stereochemistry was established bychemical correlation, spectral analysis and X-ray diffraction.     

The “Vilkov” issue

INTRODUCTION

The “Vilkov” issue     

The First Hyperpolarizabilities of Merocarbocyanines

IntroductionPhotorefractive(PR)materialscanbeusedinvariousaPplications,suchasimageprocessing,highdensityopticaldatastorage,opticalinterconnects,andopticalphaseconjugations.However,mostofthereportedPRcomPositesaredopingsystems.ThephaseseparationofcomPonentshaslimitedtheirinvestigation.Toovercomethisdisadvantage,theuseofthemulti-propertieschromophoresmaybeoneoftheeffectiveapproaches.Merocyaninesarenotonlygoodphotoconductivedyes,butalsowidelyusedaschromophoresinnonlinearopticalLBfilmsduetothe…     

The synthesis of perfluoroalkyl-substituted tetrakisphenylporphyrins

Perfluoroalkyl-substituted tetrakisphenylporphyrins were synthesized through the couplingreaction of perfluoroalkyl iodides(R_FI)with the corresponding bromophenylporphyrin under theCu-bronze catalysis.     

The Reactions of Sydnone Compounds

The duality in electronic effect of sydnone ring and the effect of delocalization of 4-substitutedgroup to sydnone ring are investigated by the nitration of 3-benzyl-4-phenylsydnone and 4-formyl-3-arylsydnones. Sydnones are typical mesoionic compounds and their chemical, physical and biological properties     

The Crystal Structure of Isosteviol

The title compound was prepared and its crystal structure was determined using X-ray crystallographic method. The crystal is orthorhombic, space group is P212121 with a= 1. 1114(2) nm, b=1.7677(3) nm, c=1.8312(3) nm; Z=8. The geometric structure and conformation of the title compound obtained by MMX molecular mechanics calculation are in agreement with those obtained from X-ray determination.     

The Origin of Alligator sinensis

Alligator sinensis and Alligator mississippiensis are put under the Alligator family and Alligator genus as two different species and have been thought that they are closely related in taxonomy. The results of our DNA-DNA hybridization experiments showed that A. sinensis is a relatively young species originated in Asia,whereas A. mississippiensis is the older.It seems that the alligator and crocodilian could evolve from each other.The evolutionary rate of the crocodilian is slower than those of birds and higher vertebrates.The phylogeny of four crocodilians have been obtained and the hypothesis that the ancestor of Crocodylus porosus is a transitional form between A.mississippiensis and A.sinensis is proposed.     

The Characteristics of Information Dimension

Based on the information theory and multifractals viewpoint, the information dimension D_1 of acoustic emission (AE) of rock for marble, gabbro and sandstone in a laboratory condition and seismic activities before and after some large earthquakes are studied. The results show that there is a dimension reduction process before the failure of rock and before the occurrence of large earthquakes. The curves of D_1 determined during the process have a wider non-scaling range. Moreover, the non-scaling range became narrow when rock was close to failure fracture and large earthquake was just to happen. This shows that the system has instable critical behavior.     

The Battle of Calicheamicin γ

The first total synthesis of calicheamicin γ was achieved approximately a year ago. In this article, the author presents a personal account of the events, in chronological order, that led to this success story in total synthesis.     

The Stereoselective Synthesis of Indoloquinolizines

Carboline was reduced with lithium aluminum hydride to provide carboline-alcohol whichreacted with methyl vinyl ketone to form the corresponding hydroxymethyl-amino-ketone. Underphase transfer condition it can be converted into enantiomerically pure indoloquinolizines. The cycliza-tion mechanism was also illustrated here.