RESUMO
A novel and practical palladium-catalyzed aerobic oxyarylthiolation of alkynone O-methyloximes for the assembly of 4-sulfenylisoxazole derivatives using S8 and arylhydrazines as the S-aryl sources is accomplished. In the presence of 0.1 mol% of IPr-Pd-allyl-Cl as the catalyst and O2 (1 atm) as the sole oxidant, both alkynone O-methyloximes and arylhydrazines are suitable substrates, delivering diverse 4-sulfenyl isoxazoles in moderate to good yields with good functional group tolerance. Notably, the phenyl diazonium salt and sodium phenyl sulfinate are also suitable arylation reagents, providing an alternative synthetic strategy to access structurally diverse 4-sulfenyl isoxazoles.
RESUMO
A gas chromatographic method was developed to directly determine the enantiomers of acrylic ketone alcohol and acrylic ketone acetate. Two pairs of enantiomers were nearly baseline-separated by using Model HP-5890 Gas Chromatograph with flame ionization detector and WCOT CD-Chiral-DEX CB (30 m x 0.25 mm i.d.) column. The optimum conditions were the split ratio of 30:1 for the sample injected, the flow rates of 3.7 mL/min for the carrier gas (nitrogen), 60 mL/min for the hydrogen, and 250 mL/min for the oxygen, and temperatures of 148 degrees C for the column, 230 degrees C for the injector, and 230 degrees C for the detector. The linearity and reproducibility were satisfactory. The regression coefficients were over 0.9965. The RSDs obtained were less than 1.25%. The method was further used to trace the reactants and products, and to evaluate the enzyme catalyst activity and selectivity under different conditions. The results show that the method developed is very successful.
