Total synthesis of optically active lycopladine A by utilizing diastereoselective protection of carbonyl group in a 1,3-cyclohexanedione derivative

We successfully synthesized two enantiomers of bicyclic enones, (7R,7aR)- and (7S,7aS)-9, from the hemiacetal 2a, which we first synthesized from the symmetrical diketone 1a via diastereoselective carbon-oxygen bond formation between one of the carbonyl groups and the chiral alcohol on the C2 side chain in a 2,2-disubstituted 1,3-cycloalkanedione derivative. We also report the total synthesis of natural (+)-lycopladine A [(+)-6] from (7R,7aR)-9 and the formal synthesis of unnatural (-)-lycopladine A [(-)-6] from (7S,7aS)-9.     

Rational synthesis of Pt spheres with hollow interior and nanosponge shell using silica particles as template

Here we report a facile and efficient method to prepare Pt spheres with hollow interior and nanosponge shell with high surface area. Such a unique Pt nanostructure can effectively improve the electrocatalytic performance of Pt catalysts by facilitating the access of electroactive species to the full-extent Pt surface.     

HPLC separation of all aldopentoses and aldohexoses on an anion-exchange stationary phase prepared from polystyrene-based copolymer and diamine: the effect of NaOH eluent concentration

To investigate the separations of all aldopentoses (ribose, arabinose, xylose and lyxose) and aldohexoses (glucose, galactose, allose, altrose, mannose, gulose, idose and talose) on the D? stationary phase prepared by the reaction of chloromethylated styrene-divinylbenzene copolymer and N,N,N',N'-tetramethyl-1,6-diaminohexane, we examined the effect of varying the concentration of the NaOH eluent on the elution orders. Separations of these aldoses were achieved using a 20 mM NaOH eluent. The elution behaviors of the aldoses were probably due to not only the individual pK(a) values, but also the chemical structures of the cyclic aldoses.     

Linking Conformational Flexibility and Kinetics: Catalytic 1,4‐Type Friedel–Crafts Reactions of Phenols Utilizing 1,3‐Diamine‐Tethered Guanidine/Bisthiourea Organocatalysts

Herein, we present details of our conformationally flexible, 1,3‐diamine‐tethered guanidine/bisthiourea organocatalysts for chemo‐, regio‐, and enantioselective 1,4‐type Friedel–Crafts reactions of phenols. These organocatalysts show a unique stereo‐discrimination governed by the differential activation entropy (ΔΔS^≠), rather than by the differential activation enthalpy (ΔΔH^≠). Extensive kinetic analyses using Eyring plots for a series of guanidine/bisthiourea organocatalysts revealed the key structural motif in the catalysts associated with a large magnitude of differential activation entropy (ΔΔS^≠). A plausible guanidine–thiourea cooperative mechanism for the enantioselective Friedel–Crafts reaction is proposed.     

Changes in Hip and Knee Muscle Strength in Patients Following Total Hip Arthroplasty

Objective: To investigate changes in hip and knee muscle strength in patients before and after total hip arthroplasty (THA) in comparison with that in healthy adults. Methods: The study included 21 women who underwent unilateral THA (THA group) and 21 age-matched healthy women (healthy group). Maximal isometric strengths of hip flexors, extensors, and abductors, and knee extensors and flexors were measured before surgery and at 4 weeks and 6 months after surgery. Results: Before surgery, muscle strength on both sides, except for hip flexors on the uninvolved side, was significantly lower in the THA group than the corresponding muscle strength in the healthy group. Up to 6 months after THA, strength of all muscle groups on both sides was significantly improved compared with their preoperative status, although the knee extensor strength on the involved side temporarily worsened at 4 weeks. However, the strength of hip extensors and knee extensors on the involved side, and hip abductors on both sides in the THA group remained below that in the healthy group. Conclusions: Our results suggest that rehabilitation specialists should consider increasing the focus on the uninvolved side and encourage patients to continue strength training beyond 6 months after surgery.