Utilization of nosylepimines of 1,6-anhydro-β-d-hexopyranoses for the preparation of halogenated aminosaccharides

Preparation of N-nosyl-3,4-epimines derived from levoglucosan by sodium borohydride reduction

“…The low temperature in sulfonylation was necessary to obtain high yields of N-o-nitrobenzenesulfonylated epimines. In comparison to nosylation of 2,3-epimines, 12 lowering of the reaction temperature from À30 to À40°C improved the yields of N-nosyl-3,4-epimines, but further decrease of the temperature to À50°C caused only retardation of the reaction.…”

“…The regioselectivity observed for reactions of N-tosylepimines (trans-diaxial ring cleavage according to the Fü rst-Plattner rule 13 ) was retained and easy N-deprotection of the resulting nosylamides with benzenethiol under alkaline conditions together with high reaction yields were achieved. 12 In this paper, we present the preparation of N-nosyl-3,4-epimines with the D D-allo, D D-galacto, and D D-talo configurations based on the reduction of vicinal azido tosylates of 1,6-anhydro-b-D D-hexopyranoses by sodium borohydride.The key step in the synthesis of the epimines was the preparation of 2-O-benzyl-3,4-epoxides of 1,6-anhydrob-D D-hexopyranoses 2,4,5 (Scheme 1), which subsequently underwent azidolysis of the oxirane ring to afford (after O-tosylation) suitably substituted (with OTs, OBn, and N 3 groups) 1,6-anhydrohexoses with D D-gluco and D Dmanno configurations (Scheme 2, azido tosylates 6-8).The dianhydrides 2-5 were obtained from levoglucosan 1 via a set of reactions already published (for a review about preparation of dianhydrides of hexopyranosessee Refs. 14 and 15).…”

“…The regioselectivity observed for reactions of N-tosylepimines (trans-diaxial ring cleavage according to the Fü rst-Plattner rule 13 ) was retained and easy N-deprotection of the resulting nosylamides with benzenethiol under alkaline conditions together with high reaction yields were achieved. 12 In this paper, we present the preparation of N-nosyl-3,4-epimines with the D D-allo, D D-galacto, and D D-talo configurations based on the reduction of vicinal azido tosylates of 1,6-anhydro-b-D D-hexopyranoses by sodium borohydride.…”

Ring‐Opening Reactions of Aziridines Fused to a Conformationally Locked Tetrahydropyran Ring

“…[19,[23][24][25] In this paper, we have extended the ring-cleavage reactions of epimines to 4-deoxy-derivatives of 1,6-anhydro-β--hexopyranoses in order to obtain deeper insight into the mechanisms actually involved in the aziridine cleavage. We have performed a series of nucleophilic ring-opening reactions on N-tosylaziridines 1 and 2 (Scheme 1) with selected nucleophiles.…”

Nucleophilic ring-opening of activated aziridines: A one-step method for labeling biomolecules with fluorine-18

“…The most often used fluorination reagents are BF 3 ÁOEt 2 [29][30][31], HF * Pyridine (Olah's Reagent) [32,33], diethylaminosulfur trifluoride (DAST) and LiBF 4 [34], TBAF [35,36], KHF 2 [37] or KF [38]. Unfortunately, for nucleophilic fluorine-18 radiolabeling, 18 Ffluorination reagents are limited.…”