Synthesis and rheological properties of star-shaped polydimethylsiloxanes based on carbosilane dendrimers

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Tackling N-Alkyl Imines with 3d Metal Catalysis: Highly Enantioselective Iron-Catalyzed Synthesis of α-Chiral Amines

A readily activated iron alkyl precatalyst effectively catalyzes the highly enantioselective hydroboration of N-alkyl imines. Employing a chiral bis(oxazolinylmethylidene)isoindoline pincer ligand, the asymmetric reduction of various acyclic N-alkyl imines provided the corresponding α-chiral amines in excellent yields and with up to >99 % ee. The applicability of this base metal catalytic system was further demonstrated with the synthesis of the pharmaceuticals Fendiline and Tecalcet.     

Novel π-conjugated structures with fluorescent properties based on 4-alkoxytetrahydroquinazoline N-oxide

Russian Chemical Bulletin - Synthetic approaches to previously unknown 4-OR-2-methyltetrahydroquinazoline N-oxides were elaborated. 4-Alkoxy- and 4-aryloxy-2-methyltetrahydroquinazoline N-oxides...     

Extending N-heterocyclic carbene ligands into the third dimension: a new type of hybrid phosphazane/NHC system

A simple, “click” synthetic approach to a new type of hybrid phosph(III)azane/NHC system is described. The presence of the phosphazane P₂N₂ ring unit, with P atoms flanking the NCN fragment and with this ring perpendicular to the binding site of the NHC, provides unique opportunities for modifying the electronic and steric character of these carbenes.     

Synthesis of novel non-natural spiro[2.3]hexane amino acids,the conformationally restricted analogs of γ-aminobutyric acid

3-Methylenecyclobutanecarboxylic acid and its methyl ester were used as the starting compounds for the synthesis of new spiro[2.3]hexane amino acids, the conformationally rigid analogs of γ-aminobutyric acid, namely, 5-aminospiro[2.3]hexanecarboxylic and 5-amino-spiro[2.3]hexanephosphonic acids, promising modulators of GABAergic cascades in the human central nervous system. The methods developed for the synthesis of the target amino acids are based on the reactions of catalytic [1+2] cycloaddition of diazoacetic and diazophosphonic esters to 3-substituted methylenecyclobutanes, as well as on a modified Curtius reaction for the transformation of a carboxy group to the amine one.     

Multiarm Star-Shaped Polydimethylsiloxanes with a Dendritic Branching Center

New multiarm stars have been synthesized based on polylithium derivatives of high-generation carbosilane dendrimers. In the synthesis of multiarm stars based on the eighth-generation dendrimer, steric hindrances were observed even during the synthesis of a polylithium initiator. Subsequently, this led to chain transfer reactions between growing arms, as well as other side effects. As a result, dense nanogel formations with a higher tendency of ordering than in classical objects of this type were isolated from the reaction mixture. The study of the rheology of multiarm stars based on sixth-generation dendrimers made it possible to determine the activation energies of viscous flow in these objects, which makes it possible to consider them as objects with a macromolecular nature and a reptation flow mechanism.     

Synthesis and some properties of 4-phosphorylated derivatives of 5-mercapto-1,3-oxazoles

Various approaches to the synthesis of new derivatives of diethyl 5-mercapto-2-R-1,3-oxazole-4-ylphosphonates were considered. The behavior of these compounds in the presence of mineral acids and alkalis resulting in the synthesis of previously unknown 5-mercapto-2-R-1,3-oxazole-4-ylphosphonic acids was studied.     

New nanomolar negative modulators of AMPA receptors

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Formation of porous matrices from lactide and ε-caprolactone copolymers in supercritical carbon dioxide medium

A series of lactide and ε-caprolactone copolymers containing 4–24 mol % of ε-caprolactone with 20- to 30-kDa molecular weights are synthesized. Based on them, porous materials are produced by foaming in supercritical carbon dioxide. The pore size was shown to decrease with increasing ε-caprolactone content in copolymer, while the porosity of the entire sample was not altered. The resulting pore size also decreases if 7 wt % polyethylene glycol is added to the initial monomer mixture. The Young’s modulus of the porous samples decreases with increasing ε-caprolactone content and when polyethylene glycol is added.     

Synthesis of 3-amino-1-benzyl-4-benzenesulfonyl-2-carbonitrilo-1H-pyrrole and preparation of related pyrrolo[3,2-d]pyrimidines

A method for the synthesis of a new 4-phenylsulfonyl-substituted 3-aminopyrrole was developed and related pyrrolo[3,2-d]pyrimidine derivatives were synthesized.