Artificial nucleosides possessing metal binding sites at the 3'- and 5'-positions of the deoxyribose moieties

This paper describes a convenient synthetic procedure for nucleoside mimics, 1-6, in which the 3',5'-hydroxy groups of natural 2'-deoxythymidine or 2'-deoxyadenosine are replaced by thiol, amine, or alkylthiol groups. Such nucleosides would be built up into a single DNA strand with cooperative participation of metal coordination, where internucleoside linkages are replaced by metal complexation motifs. The X-ray crystal structure and complexation behaviors of 3',5'-dithiothymidine, 1, with Au(I) are also reported.     

Extensions between finite-dimensional simple modules over a generalized current Lie algebra

We calculate the first extension groups for finite-dimensional simple modules over an arbitrary generalized current Lie algebra, which includes the case of loop Lie algebras and their multivariable analogs.     

Permeability enhancement of stratified metal dielectric metamaterial in optical regime

Magnetic response of stratified metal dielectric metamaterial (SMDM) is demonstrated numerically and experimentally. One unit cell of SMDM has a sandwich unit cell consisting of alumina (60 nm)/silver (30 nm)/alumina (60 nm). A Mach–Zehnder interferometer is used to obtain phase information of transmittance and reflectance from which effective permeability is determined. The maximum permeability amounts to 20 and 17 for calculation and experiment, respectively. This huge resonance occurs when the magnetic field is concentrated at the metal layer, while the electric field has a node at the center.     

Metallocene bis(perfluoroalkanesulfonate)s as air-stable cationic Lewis acids

Zirconocene and titanocene bis(perfluorooctanesulfonate)s were synthesized. In contrast to the corresponding triflates and perchlorates, these compounds are air- and water-stable. They were proved to be ionic on the basis of conductivity measurements and X-ray analysis, allowing these complexes to be stored for months. The strong Lewis acidity of these cationic metallocene species, which was proved by ESR study, enabled catalytic glycosylation.     

Enantioselective desymmetrization of meso-N-(heteroarenesulfonyl)aziridines with TMSN3 catalyzed by chiral Lewis acids

A catalytic enantioselective desymmetrization of meso-N-(heteroarenesulfonyl)aziridines with TMSN₃ using chiral Lewis acids afforded products with high enantioselectivity. As proof of the utility of this procedure, the precursor of selective κ-opioid agonist (1S,2S)-(−)-U-50,488 was synthesized.     

One-pot synthesis of optically active allyl esters via lipase-vanadium combo catalysis

The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution.     

A possible interpretation of CDF dijet mass anomaly and its realization in supersymmetry

Recently, the CDF Collaboration reports an anomaly in dijet mass distribution in association with a lepton and missing energy. We discuss a possibility that the origin of the lepton and missing energy comes not from a W boson but a new boson particle, which is also responsible for the dijet mass peak. We show that such a situation can be realized in the framework of the minimal supersymmetric standard model and the dijet anomaly can be explained.     

Synthesis and DNA-recognition behavior of a novel peptide ribonucleic acid with a serine backbone (oxa-PRNA)

(2S)-2-Fmoc-amino-3-(5′-deoxyuridinylamino)-3-oxopropyloxyacetic acid was synthesized from l-serine as a monomer for preparing the second-generation peptide ribonucleic acid with an oxa-peptide backbone (oxa-PRNA). The ether linkage was incorporated to improve the modest solubility in aqueous solution of the original PRNA with an iso-glutamine backbone, without harming the ability of the amino-uridine side chain to switch the anti/syn nucleobase orientation by adding borax. Indeed, CD spectral examinations revealed that the Fmoc-protected oxa-PRNA uridine monomer (Fmoc-oxa-PRNA(U)), synthesized in three steps, switched the nucleobase orientation from anti to syn in phosphate buffer upon addition of borax. Homo-12mers of oxa-PRNA(U) with and without Arg end caps were prepared in moderate yields by the Fmoc solid-phase synthesis. Both of the N- and C-terminus-capped oxa-PRNA(U) 12mers thus synthesized were shown to hybridize with the complementary DNA 12mer (d(A₁₂)) with stabilities comparable to that observed for the natural pair.