Synthesis of Novel C_(2)-Symmetrical Bidentate Phosphoramidite Ligands for Rh-catalyzed Asymmetric Hydrogenation of β-(Acylamino)acrylates

Two new C2-symmetrical bidentate phosphoramidite ligands were synthesized and employed in the Rh-catalyzed asymmetric hydrogenation of β-（acylamino）acrylates, up to 89% ee with full conversions was obtained.

Enantioselective Rh-Catalyzed Hydrogenation of N-Acyl Dehydroamino Esters and Enamides with Monodentate Phosphoramidite Ligands

Chiral monodentate phosphoramidite ligands were conveniently prepared from 1,1＇-bi-2-naphthol （BINOL） and （S）-pyrrolidine in good yields, which were effective chiral ligands in the enantioselective rhodium-catalyzed hydrogenation of dehydroamino esters and enamides at low hydrogenation pressure. High conversion rate （up to 99% for dehydroamino esters and enamides） and good enantioselectivity （up to 96.3% ee for dehy- droamino esters and 91.7% ee for enamides） were obtained.

Synthesis of O -Phosphorylated Oligopeptides Using Phosphoramidite

Reversible protein phosphorylation is of great importance in the regulation of many cellular processes. Structurally well defined compounds are needed for the study of the roles of the phospho proteins in biological processes. In this paper, O phosphorylated oligopeptides were synthesized using bis alkyloxy N,N dialkylphosphoramidite reacting with the oligopeptide followed by oxidation. Many hydroxyl groups in oligopeptides can be phosphorylated in one step.

^(11)B and ~7Li NMR Investigations of the Oxysulfide Glasses in Li_2S-B_2O_3 (-LiBr) Systems

Phosphopeptides were synthesized with bis-alkyloxy-N,N-dialkylphosphorfollowed by oxidation. Many hydroxyl groups in oligopeptides can be O-phosphorylated in onestep.

Synthesis of RNA-Amphiphiles via Atom Transfer Radical Polymerization in the Organic Phase

The combination of hydrophobic polymers with nucleic acids is a fascinating way to engineer the self-assembly behavior of nucleic acids into diverse nanostructures such as micelles,vesicles,nanosheets,and worms.Here we developed a robust route to synthesize a RNA macroinitiator with protecting groups on the 2′-hydroxyl groups in the solid phase using an oligonucleotide synthesizer.The protecting groups successfully solubilized the RNA macroinitiator,enabling atom transfer radical polymerization(ATRP)of hydrophobic monomers.As a result,the RNA−polymer hybrids obtained by ATRP exhibited enhanced chemical stability by suppressing cleavage.In addition,we demonstrated evidence of controlled polymerization behavior as well as control over the molecular weight of the hydrophobic polymers grown from RNA.We envision that this methodology will expand the field of RNA−polymer conjugates while vastly enhancing the possibility to alter and engineer the properties of RNA-based polymeric materials.

Iridium-Catalyzed Allylic Alkylations of Sodium Phenyl Selenide

An iridium-catalyzed allylic substitution of sodium phenyl selenide with unsymmetrical allyl carbonates was accomplished, which produced the linear allyl phenyl selenides in 38%--74% yields. An asymmetric irid- ium-catalyzed allylation of sodium phenyl selenide was presented as well.

Atroposelective sp3 C—H Coupling for Kinetic Resolution of Thioanilide Atropisomers

A highly efficient kinetic resolution of racemic thioanilide atropisomers via C(sp^(3))-H arylation has been achieved by a hybrid palladium catalyst bearing an anionic chiral Co^(Ⅲ)-complex and a phosphoramidite ligand,leading to both enantioenriched atropisomeric arylation thioanilides(up to 99%ee)and N-Me atropisomeric thioanilides(up to 99%ee),simultaneously.The remained enantioenriched substrates can be arylated again by using an achiral anionic ligand to give the enantiomer with the opposite configuration.

Platinum-Catalyzed Allylic C-H Alkylation with Malononitriles

The direct functionalization of allylic C-H bonds is distinguished by enabling rapid assembly of structural complexity from simple molecules.Although Pd-catalyzed allylic C-H functionalization has been extensively studied,the discovery of new catalytic systems remains fairly underdeveloped.Here,we disclose a Pt-catalyzed allylic C-H alkylation of a wide range of α-alkenes by using phosphoramidites as ligands and malononitriles as alkylating reagents.Notably,the combination of chiral ureacatalyzed Michael addition and Pt-catalyzed allylic C-H alkylation can serve as an efficient protocol to access chiral tetrahydropyran with high levels of diastereo-and enantioselectivity.Mechanistic studies suggest that the Pt-catalyzed allylic C-H activation proceeds through a concerted proton and two-electron transfer process,which is analogous to transition state geometries of Pd catalysis.

A highly efficient fluorescence-based switch-on detection method of 5-formyluracil in DNA

The identification of hydroxylmethyl- and formylpyrimidines in genomic DNA was a landmark event in epigenetics. Numerous laboratories in related fields are investigating the biology of these and other nucleic acid modifications. However, limitations in the ability to detect and synthesize appropriate modifications are an impediment. Herein, we explored a remarkable development in the selective detection of 5-formyluracil in both single-stranded and double-stranded DNA under mild conditions. The ＂switch-on＂ specificity towards 5-formyluracil enabled a high signal-to-noise ratio in qualitatively and quantitatively detecting materials containing 5-formyluradl, which is not affected by the presence of abasic sites and 5-formylcytosine, the modified cytosine counterpart of 5-formyluracil. In summar~ the innoxiousness, convenience, and cost-effidency of the 5-formyluracil phosphoramidite synthetic routine would promote the understanding of the epi^enetic role of this natural thvmidine modification.

Large scale synthesis of oligoribonucleotides on PEG by the phosphite triester approach

Large scale synthesis of oligoribonucleotides has been successfully performed on PEG support by the phosphoramidite approach using t-butyldimethylsilyl to protect the 2'-hydroxyl group of ribonucleoside. By means of this procedure, the dodecamer r(AGUGGUCUUUGU) was synthesized in 98.1% average coupling yield, and 55 mg pure product was obtained from one gram of functionalized PEG.

A novel method for the synthesis of sulfur substituted-cyclopyrophosphate of cADPR analogs

A facile and efficient protocol for the synthesis of sulfur substituted-cyclopyrophosphate of cIDPRE（P_S^1-cIDPRE） was developed.The key step was the cyclization process which was completed by the sulfur substituted cyclization precursor 1b via the one-pot phosphoramidite strategy.