Novel lipase-catalyzed ring-opening copolymerization of oxiranes and succinic anhydride forming polyesters bearing functional groups

Oxiranes, such as glycidyl phenyl ether (GPE) and benzyl glycidate (BG), were copolymerized with succinic anhydride (SA) by lipase at a temperature between 60 and 80°C to yield the corresponding polyesters bearing carboxyl or phenyl groups. Bulk polymerization, especially at the temperature of 80°C, and preferably using porcine pancreatic lipase gave biodegradable polyesters with a molecular weight greater than 5000.     

Beckman rearrangement of oxime sulfonates by grignard reagents

The Beckmann rearrangement of oxime sulfonates by Grignard reagents provides an efficient and general entry to α-alkyl- and α,α-dialkylamines in good yields.     

Enzyme‐Catalyzed Preparation of Aliphatic Polythioester by Direct Polycondensation of Diacid Diester and Dithiol

Summary: Aliphatic dithiol‐diacid type polythioesters were first enzymatically prepared by the direct polycondensation of hexane‐1,6‐dithiol and diacid diesters using the immobilized lipase from Candida antarctica (lipase CA). As a typical example, diethyl sebacate and hexane‐1,6‐dithiol were polymerized using lipase CA in bulk in the presence of molecular sieves 4A to produce the corresponding polythioester with an of 10 200 in 90% yield. Both the melting and crystallization temperatures of the produced polythioesters were higher when compared to those of the corresponding polyoxyesters. A higher molecular weight polythioester was produced using lipase in a two‐step procedure, i.e., cyclization with subsequent ring‐opening polymerization.

Preparation of polythioester and melting temperature of various polythioesters and polyoxyesters.     

Magnetic phase transition in a heteromolecular hydrogen-bonded complex of nitronylnitroxide radicals

An organic molecular acid-base complex has been synthesized from pyridine-substituted biradical 2 in a triplet (S = 1) ground state and a benzoic acid derivative of monoradical 3 with S = 1/2. The two constituent molecules are bound by an OH-N hydrogen bond in a crystalline solid state. The complex has been found to exhibit an antiferromagnetic phase transition at 5 K. The complex is the first example of a hydrogen-bonded heterospin, heteromolecular complex exhibiting a magnetic phase transition in purely organic molecule-based materials.     

Magnetic interaction of tri- and di-oxytriphenylamine radical cation FeCl4 salts

The tetrachloroferrates of the 2,2':6',2':6',6-trioxytriphenylamine (TOT.+.FeCl4-) and 2,2':6',2'-dioxytriphenylamine (DOT.+.FeCl4-) radical cations were prepared, and their structures, magnetic properties, and the relationship between them were investigated. The TOT.+ moiety had a highly planar structure and packed as a dimer surrounded by tetrachroferrates, which also formed a dimer structure. The magnetic properties of TOT.+.FeCl4- were characterized by strong (2J/kB=approximately -1.3x10(3) K, H=-2JS1/2.S1/2) and weak (2J/kB=-1.76 K, H=-2JS5/2.S5/2) antiferromagnetic interactions due to the (TOT.+)2 and (FeCl4-)2 structures, respectively. DOT.+ had a twisted form and no dimer formation was observed between the DOT.+'s and FeCl4-'s. Instead, short contacts between the DOT.+ and chlorine atoms and between the DOT.+'s producing a DOT.+ chain were observed. The magnetic properties of DOT.+.FeCl4- were characterized by a 3D magnetic phase transition to an antiferromagnet with TN=approximately 8 K.     

DABCO-triggered mild cascade reaction of electron-deficient cyclopentadienone: facile and efficient synthesis of condensed carbocycles

2,5-Bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone (1) reacts with 4-phenylbut-3-yn-2-one (2b) in the presence of DABCO to give the bicyclic carbocycles (6b) and the tetracyclic carbocycle (7b) under extremely mild reaction conditions.     

Photodegradation of lipopolysaccharides and the inhibition of macrophage activation by anthraquinone-boronic acid hybrids

Target-selective photodegradation of 3-deoxy-D-manno-2-octulopyranosonic acid (KDO) was achieved without additives and under neutral conditions using a designed anthraquinone-boronic acid hybrid and long wavelength UV light irradiation. The hybrid can photodegrade lipopolysaccharides (LPS) and inhibit macrophage activation induced by LPS.