15451-81-7Relevant articles and documents
Site-Selective Acylation of Pyranosides with Oligopeptide Catalysts
Seitz, Alexander,Wende, Raffael C.,Roesner, Emily,Niedek, Dominik,Topp, Christopher,Colgan, Avene C.,McGarrigle, Eoghan M.,Schreiner, Peter R.
, p. 3907 - 3922 (2021/03/09)
Herein, we report the oligopeptide-catalyzed site-selective acylation of partially protected monosaccharides. We identified catalysts that invert site-selectivity compared to N-methylimidazole, which was used to determine the intrinsic reactivity, for 4,6
In Situ Switching of Site-Selectivity with Light in the Acetylation of Sugars with Azopeptide Catalysts
Eckhardt, André K.,Erb, Frederik R.,Herold, Dominik,Kind, Jonas,Niedek, Dominik,Schreiner, Peter R.,Seitz, Alexander,Thiele, Christina M.,Topp, Christopher,Wende, Raffael C.
supporting information, (2020/02/04)
We present a novel concept for the in situ control of site-selectivity of catalytic acetylations of partially protected sugars using light as external stimulus and oligopeptide catalysts equipped with an azobenzene moiety. The isomerizable azobenzene-peptide backbone defines the size and shape of the catalytic pocket, while the π-methyl-l-histidine (Pmh) moiety transfers the electrophile. Photoisomerization of the E- to the Z-azobenzene catalyst (monitored via NMR) with an LED (λ = 365 nm) drastically changes the chemical environment around the catalytically active Pmh moiety, so that the light-induced change in the catalyst shape alters site-selectivity. As a proof of principle, we employed (4,6-O-benzylidene)methyl-α-d-pyranosides, which provide a change in regioselectivity from 2:1 (E) to 1:5 (Z) for the monoacetylated products at room temperature. The validity of this new catalyst-design concept is further demonstrated with the regioselective acetylation of the natural product quercetin. In situ irradiation NMR spectroscopy was used to quantify photostationary states under continuous irradiation with UV light.
Ceric ammonium nitrate/acetic anhydride: A tunable system for the O-acetylation and mononitration of diversely protected carbohydrates
Seepersaud, Mohindra,Seecharan, Savita,Lalgee, Lorale J.,Jalsa, Nigel Kevin
supporting information, p. 853 - 871 (2017/04/27)
Esterification of a wide range of partially protected carbohydrate derivatives was achieved using acetic anhydride and a catalytic amount of ceric ammonium nitrate (CAN). Compatibility with the commonly used protecting groups was demonstrated, with the es
