Structural-Functional Properties of Asymmetric Fluoro-Alkoxy Substituted Benzothiadiazole Homopolymers with Flanked Chalcogen-Based Heterocycles.

The synthesis and characterization of asymmetric alkoxy- are reported, fluoro-benzothiadiazole (BT) acceptor core derivatized with a series of six different heterocycles (selenophene, thiophene, furan, 5-thiazole, 2-thiazole and 2-oxazole). The effect of the flanked-heterocycles containing different chalcogen atoms of the six homopolymers (HPX) is studied using optical, thermal, electrochemical, and computational analysis. Computational calculations indicate a strong relationship between the most stable conformation for each homopolymer and their bearing heterocycle, thus homopolymers HPSe', HPTp', HPFu', and HPTzC5, adopted the syn-syn and syn-anti conformations due to their noncovalent interactions with shorter distances, while HPTzC2' and HPOx' demonstrate preference for the anti-anti conformation.

Electron-Deficient Polycyclic π-System Fused with Multiple B←N Coordinate Bonds.

An extensive polycyclic π-system with 23 fused rings is synthesized via a highly efficient borylation reaction, in which four B-N covalent bonds and four B←N coordinate bonds are formed in one pot. B←N coordinate bonds not only lock the backbone into a near-coplanar conformation but also decrease the LUMO energy level to around -3.82 eV, demonstrating the dual utility of this strategy for the synthesis of extensive rigid polycyclic molecules and the development of -type conjugated materials for organic electronics and organic photovoltaics.

Synthesis of TPEN variants to improve cancer cells selective killing capacity.

TPEN is an amino chelator of transition metals that is effective at the cellular and whole organism levels. Although TPEN of often used as a selective zinc chelators, it has affinity for copper and iron and has been shown to chelate both biologically. We have previously shown that TPEN selectively kills colon cancer cells based on its ability to chelate copper, which is highly enriched in colon cancer cells.

Modular Strategy To Expand the Chemical Diversity of DNA and Sequence-Controlled Polymers.

Sequence-defined polymers with customizable sequences, monodispersity, substantial length, and large chemical diversity are of great interest to mimic the efficiency and selectivity of biopolymers. We report an efficient, facile, and scalable synthetic route to introduce many chemical functionalities, such as amino acids and sugars in nucleic acids and sequence-controlled oligophosphodiesters. Through achiral tertiary amine molecules that are perfectly compatible with automated DNA synthesis, readily available amines or azides can be turned into phosphoramidites in two steps only.

DNA-imprinted polymer nanoparticles with monodispersity and prescribed DNA-strand patterns.

As colloidal self-assembly increasingly approaches the complexity of natural systems, an ongoing challenge is to generate non-centrosymmetric structures. For example, patchy, Janus or living crystallization particles have significantly advanced the area of polymer assembly. It has remained difficult, however, to devise polymer particles that associate in a directional manner, with controlled valency and recognition motifs.

Correction: Antisense precision polymer micelles require less poly(ethylenimine) for efficient gene knockdown.

Correction for 'Antisense precision polymer micelles require less poly(ethylenimine) for efficient gene knockdown' by Johans J. Fakhoury, et al., Nanoscale, 2015, 7, 20625-20634.

Antisense precision polymer micelles require less poly(ethylenimine) for efficient gene knockdown.

Therapeutic nucleic acids are powerful molecules for shutting down protein expression. However, their cellular uptake is poor and requires transport vectors, such as cationic polymers. Of these, poly(ethylenimine) (PEI) has been shown to be an efficient vehicle for nucleic acid transport into cells.

Palladium-catalyzed stereoselective intramolecular oxidative amidation of alkenes in the synthesis of 1,3- and 1,4-amino alcohols and 1,3-diamines.

An efficient and practical Pd-catalyzed intramolecular oxidative allylic amidation provides facile access to derivatives of 1,3- and 1,4-amino alcohols and 1,3-diamines. The method operates under mild reaction conditions (RT) with molecular oxygen (1 atm) as the sole reoxidant of Pd. Excellent diastereoselectivities were attained with substrates bearing a secondary stereogenic center.

Palladium-catalyzed alkoxycarbonylation of terminal alkenes to produce α,β-unsaturated esters: the key role of acetonitrile as a ligand.

A mild protocol has been developed for the Pd(II)-catalyzed alkoxycarbonylation of terminal olefins to produce α,β-unsaturated esters with a wide range of substrates. Key features are the use of MeCN as solvent (and/or ligand) to control the reactivity of the intermediate Pd complexes and the combination of CO with O2, which facilitates the Cu(II)-mediated reoxidation of the Pd(0) complex to Pd(II) and prevents double carbonylation.

Stereoselective palladium-catalyzed functionalization of homoallylic alcohols: a convenient synthesis of di- and trisubstituted isoxazolidines and β-amino-δ-hydroxy esters.

Enantiopure, Boc-protected alkoxyamines 12 and 13, derived from the readily available homoallylic alcohols 4 via a reaction that involves either inversion or retention of configuration, undergo a diastereoselective Pd-catalyzed ring-closing carbonylative amidation to produce isoxazolidines 16/17 (≤50:1 diastereoisomer ratio (d.r.)) that can be readily converted into the N-Boc-protected esters of β-amino-δ-hydroxy acids and their γ-substituted homologues 37.

Enantioselective allylation of α,β-unsaturated aldehydes with allyltrichlorosilane catalyzed by METHOX.

α,β-Unsaturated aldehydes 6a-j undergo an enantioselective allylation with allylic trichlorosilanes 2a,b in the presence of METHOX (4) as a Lewis basic catalyst (≤10 mol %) to produce the homoallylic alcohols 7a-l at good to high enantioselectivity (83-96% ee). This study shows that the reactivity scope of METHOX can be extended from aromatic to nonaromatic aldehydes.

Enantioselective and catalytic method for alpha-crotylation of aldehydes with a kinetic self-refinement of stereochemistry.

Kinetic refinery: A practical, highly stereoselective, two-step catalytic protocol for the alpha-allylation of aldehydes, starting from crotyltrichlorosilanes, has been developed (see scheme). In each reaction step, one of the stereoisomers reacted faster than the other, which resulted in a kinetic stereochemical (E/Z) self-refinement of the system and led to the formation of virtually enantiomerically and geometrically pure linear homoallylic alcohols in high yield.