A Brønsted acid catalyst for the enantioselective protonation reaction

A highly reactive and robust chiral Br?nsted acid catalyst, chiral N-triflyl thiophosphoramide, was developed. The first metal-free Br?nsted acid catalyzed enantioselective protonation reaction of silyl enol ethers was demonstrated using this chiral Br?nsted acid catalyst. The catalyst loading could be reduced to 0.05 mol % without any deleterious effect on the enantioselectivity.     

Algebraic hulls of solvable groups and exponential iterated integrals on solvmanifolds

We represent the coordinate ring of algebraic hulls (which are the fundamental groups of generalizations of the Malcev completions of nilpotent groups for solvable groups) of solvmanifolds G/Γ by using Miller’s exponential iterated integrals (which are extensions of Chen’s iterated integrals) of invariant differential forms.     

Chemical modification of hydroxyl groups of poly(vinyl alcohol) by a glycosidation reaction

A new procedure for chemical modification of poly(vinyl alcohol) (PVA) was established by a glycosidation reaction of hydroxyl groups in PVA with triacetylated sugar oxazoline 1 . ¹H and ¹³C NMR analyses indicated that triacetylated N‐acetyl‐D‐glucosamine (GlcNAc) was introduced onto a PVA backbone selectively via a β‐O‐glycoside linkage. Deacetylation of triacetylated GlcNAc‐substituted PVA 2 resulted in GlcNAc‐substituted PVA 3 in good yield. These modified PVAs 2 and 3 exhibited solubilities and thermal properties different from the original PVA.