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Highly enantioselective palladium-catalyzed asymmetric allylic alkylation using a novel chiral pyrrolidinyl-containing amino-phosphine ligands having a hydroxyl group is described. The trialkylsilylated aminophosphine ligand gave good results in the palladium-catalyzed asymmetric allylic alkylation.

We developed a chiral symmetry breaking method for monoacylated meso diols. The X‐ray crystal structure analysis of monoacylated 1,4‐anhydroerythritols, meso cyclic diols with a cis configuration, revealed that the O‐(p‐anisoyl) derivative crystallized as a racemic conglomerate of the P212121 crystal system. It was confirmed that the substrate racemized by intramolecular transfer of the acyl group in the presence of a catalytic amount of base. Evaporating the solvent gradually from the solution or Viedma ripening to promote crystallization‐induced deracemization efficiently led to enantiomer crystals. These results provide the first successful example of asymmetric expression and amplification by deracemization of sugar derivatives without an external chemical chiral source. Furthermore, we applied this methodology to acyclic meso‐1,2‐diols. Three O‐monoacylated substrates were successfully deracemized to 99 % ee by Viedma ripening. We also developed asymmetric desymmetrization of meso‐1,2‐diols by combining acylation and crystallization‐induced deracemization. [ABSTRACT FROM AUTHOR]

Asymmetric construction of chiral N,S‐acetal skeletons is important because they are widely present in natural products and pharmaceuticals. Halogen‐bonding is a unique interaction that has been an organic synthesis focus, although research into chiral variants is limited. Halonium salts have been found to act as halogen‐bonding catalysts and asymmetric catalysis using chiral bromonium salts under basic conditions was recently discovered by our group. Herein, we report the asymmetric syntheses of chiral N,S‐acetals in good‐to‐excellent yields and enantioselectivities (82–97% ee) through bulky thiol additions to imines catalysed by a chiral iodonium salt under neutral conditions. The reaction mechanism was studied using NMR experiments and DFT calculations of a plausible intermediate, which revealed that the imine substrate is activated by the catalyst in a bidentate manner. The abnormal counteranion effect observed for the tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate anion in the present system was examined by 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

A new type of photodimerization of nicotinic acid esters to generate cage-type photodimers, in the scheme of photochemicl cycloaddition of aromatic compounds and its application to heteroaromatics, is described. The process involving 2-alkoxynicotinates leads to C2-symmetrical cage-type photodimers

Research into the photochemical reaction of aromatic compounds is presented, with reference to photo-cycloaddition of 1-cyanonaphthalene with substituted pyridines.

Microbial community changes in biological phosphate-removal systems and their effects in altering sludge phosphorus content are discussed. Biomarkers and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 165 rRNA genes have been used to characterize the microbial community structure of lab-scale enhanced biological phosphate-removal (EBPR) systems in response to altering sludge phosphorus content. Phylogenetic analysis was used.

Atroposelective resolution for axially chiral nicotinamides was achieved by dynamic chiral salt formation with L‐DBTA using six types of nicotinamides that could not be optically resolved by the preferential crystallization method. Kinetic studies of their racemization indicated that the chiral conformation was retained for a significant period of time. Two methods of crystallization‐induced asymmetric transformation were examined by dynamic diastereomeric salt formation: solvent evaporation from a supersaturated solution, and attrition‐enhanced asymmetric transformation. The attrition method was more effective for asymmetric amplification of diastereomeric salts of axially chiral materials. Attrition of equimolar amount of the nicotinamide salts with L‐DBTA converged to one diastereomer salts, and the corresponding enantiomers in 87–99 % ee were obtained after the chiral acid was removed. Changing the ratio of two of the nicotinamides with L‐DBTA to 1 : 2 inverted the axial chirality. [ABSTRACT FROM AUTHOR]

What is known and objective: Propofol is the most commonly used intravenous anaesthetic worldwide and is considered to be safe for all ages. However, there have been some reports that propofol induces severe atrioventricular (AV) blocks in humans and some studies demonstrated that propofol suppressed the cardiac conduction system in animals. A precise mechanism by which the block is induced has not been elucidated yet in humans. The objective of this study was to investigate the effects of propofol on the cardiac conduction system and the cardiac autonomic nervous balance in children. Methods: We enrolled 23 paediatric patients (age: 6‐15 years; males: 16, females: 7) who were scheduled to undergo radiofrequency catheter ablation (RFCA) under general anaesthesia. Anaesthesia was induced with 2 mg/kg propofol and 0.5 µg/kg/min remifentanil, and tracheal intubation was performed with the aid of 1 mg/kg rocuronium. Anaesthesia was maintained with 5‐7 mg/kg/h propofol and 0.2 µg/kg/min remifentanil during the RFCA. After the completion of the RFCA, anaesthesia was further maintained with 5 mg/kg/h propofol and 0.2 µg/kg/min remifentanil for at least 10 min (LC: low propofol concentration state), followed by the injection of 2 mg/kg propofol and the infusion of 10 mg/kg/h propofol for 10 min (HC: high propofol concentration state). The sinus node recovery time (SNRT), sinoatrial conduction time (SACT), atrial‐His (AH) interval and the His‐ventricular (HV) interval were measured at the end of both the LC and HC. Cardiac autonomic regulation was simultaneously assessed based on heart rate variability. Results and discussion: Propofol significantly suppressed intrinsic cardiac HV conduction, but did not affect the SNRT, SACT or the AH interval. As HV blocks, which occur below the His bundle, are often life‐threatening, the HV conduction delay may be a cause of severe AV blocks induced by propofol. Propofol directly suppressed parasympathetic nerve activity, and sympathetic nerve activity was also suppressed. What is new and conclusion: These results indicate that propofol suppresses the HV conduction and might help to elucidate the mechanism by which propofol causes lethal AV blocks. [ABSTRACT FROM AUTHOR]

We synthesized a series of phosphine–olefin-type chiral aminophosphines, and we confirmed that these each exists as two rotamers at the C(aryl)–N(amine) bond. We also investigated the ability of these aminophosphines to act as chiral ligands for Pd-catalyzed asymmetric allylic substitution reactions, such as the alkylation of allylic acetates with malonates or indoles, and we found they gave high enantio-selectivities (up to 98% ee). [ABSTRACT FROM AUTHOR]

Bromonium salts have been typically but infrequently used in various reactions as good leaving groups or as aryl or vinyl transfer reagents owing to their extremely high nucleofugality. Herein, we report the synthesis of novel, stable bromonium salts and their first catalytic application to the Michael reaction, with excellent product yield (up to 96%). [ABSTRACT FROM AUTHOR]

Research has been conducted on the 1,3-diphenyl-2-propenyl acetate. The palladium-catalyzed asymmetric allylic alkylation of this acetate with the dimethyl malonate-BSA-LiOAc system and its derivatives has been performed in the presence of the chiral ligands and the results are presented.