Regioselective pivaloylation of N-phthaloylchitosan: a promising soluble intermediate for chitosan chemistry.

A simple and efficient pivaloylation of primary alcohols was realized on N-phthaloylchitosan that was regioselectively and entirely protected. The selectivity of this mild esterification was demonstrated by comparison with (1)H NMR chemical shifts of H-1 and H-3 of complete 3,6-O-dipivaloylated derivatives. The selective hydrazinolysis of N-phthaloyl groups in the presence of pivaloyl ester was achieved in ethanol/water.

Obstetric and perinatal complications in placentas with fetal thrombotic vasculopathy.

Fetal thrombotic vasculopathy (FTV) is a placental lesion characterized by regionally distributed avascular villi and is often accompanied by upstream thrombosis in placental fetal vessels. Previous studies, using preselected populations, have shown associations of this lesion with adverse neurodevelopmental outcomes and potentially obstructive lesions of the umbilical cord. We investigated the prevalence of obstetric complications, perinatal disease, and placental abnormalities in cases with FTV.