Metal-Free Synthesis of Acyl Glycosides and Application to Oligosaccharide Synthesis.

Oligosaccharides are involved in numerous biological processes. Achieving optimal anomeric selectivity and regioselectivity remains challenging. Herein, we present a method for the oxidative glycosylation of thioglycosides with hypervalent iodine reagents derived from carboxylic acid to form C-O bonds. The reaction of thioglycosides with various hypervalent iodine carboxylates afforded acyl O-glycosyl compounds. These acyl O-glycosyl compounds could react with thioglycoside acceptors to produce disaccharides; trisaccharides and tetrasaccharides could be synthesized by repeating this method.

Cyclic Hypervalent Iodine-Induced Oxidative Phenol and Aniline Couplings with Phenothiazines.

C-H/N-H bond functionalization for direct intermolecular aryl C-N couplings is a useful synthetic process. In this study, we achieved metal-free cross-dehydrogenative coupling of phenols and anilines with phenothiazines using hypervalent iodine reagents. This method affords selective amination products under mild conditions. Electron-rich phenols and anilines could be employed, affording moderate-to-high yields of N-arylphenothiazines. Aniline amination proceeded efficiently at 20 °C, a previously unreported phenomenon.

The relationship of maternal PCB, toxic, and essential trace element exposure levels with birth weight and head circumference in Chiba, Japan.

Maternal exposure to high levels of persistent organic pollutants (POPs) and trace elements is an important concern for fetal growth. In our previous study, we showed the polychlorinated biphenyl (PCB) levels in maternal serum from the Chiba Study of Mother and Child Health (C-MACH) cohort and their relationships between PCB levels in cord serum with birth weight of newborn. Various reports on the relationship between chemical exposure and birth status have been published; however, studies that analyze the effects of both PCB and metal exposure together in one cohort are still limited. In this study, we aimed to determine the relationship of maternal serum levels of PCBs and toxic and essential trace elements [mercury (Hg), manganese (Mn), selenium (Se), and cadmium (Cd)], with birth weight and head circumference, in the C-MACH cohort. The median concentration of total PCBs in maternal serum around 32 gestational weeks (n = 62) was 360 pg g-1 wet wt (41 ng g-1 lipid wt). The levels of Hg, Mn, Se, and Cd in maternal serum were 0.89, 0.84, 100, and 0.024 ng g-1, respectively. In this study, the Bayesian linear model determined the relationships of the birth weight and head circumference with combinations of PCB levels, toxic and essential trace elements, and questionnaire data. We found that PCB concentrations in maternal serum were weakly and negatively related to birth weight, whereas trace elements were not associated with birth weight. Serum PCB and Mn levels were negatively associated with head circumference, whereas other trace elements were not associated with head circumference. These results showed that maternal exposure to PCBs may be related to birth weight and head circumference, while maternal exposure to Mn is related to head circumference, even when adjusted based on the exposure levels of other contaminants, and maternal and fetal characteristics. Therefore, our findings indicate that maternal exposure to PCBs and Mn might be negatively related with birth weight and head circumference.