HF-Induced Intramolecular C-Arylation and C-Alkylation/Fluorination of 2-Aminoglycopyranoses

Abstract

Internal C-aryl and C-alkyl glycosides derived from 2-aminoglycopyranoses have been synthesized, exploiting a HF-mediated stereoselective intramolecular glycosylation. These conditions are compatible with acetate protecting groups and allow introduction of aromatics with various electronic distributions at the anomeric position. This strategy also provides straightforward entry to original fluorinated sugar-azacycle hybrids via a tandem internal C-glycosylation/fluorination reaction starting from 2-N-allyl/propargyl glycopyranoses. All cyclizations proceed in a 1,2-cis stereocontrolled manner.

Diethylaminosulfur Trifluoride (DAST)-Mediated Intramolecular Benzannulation of o-Allylchalcones: Synthesis of 3-Fluorotetralins

“…Among them, there are few reports on the synthesis of mono-fluorinated bicycles by different fluorinating reagent-promoted intramolecular tandem cyclization/fluorination processes, as shown in Scheme 1. [14][15][16][17][18][19][20][21] These elegant synthetic routes have exhibited some advantages, including easy operation, high sitespecific selectivity, and optimal reaction conditions.…”

HF Fluorination for the Synthesis of Alkyl Fluorides

“…Thus, the reaction of peracetylated N-benzyl-b-D-2-aminoglucopyranose (1) in neat HF at À20 C for 25 h results in the formation of the Friedel-Crafts product 2 along with the fluorinated product 3 in a ratio 3:1. [8] However, the corresponding N-tosylamine derivative 4 affords the tricyclic product as the exclusive product in high yields at relatively much shorter reaction time (88% yield in 15 min at À40 C) (Fig. 2).…”

“…N-propargyl derivatives of the latter compounds give the corresponding fluoro olefins under these reaction conditions; for example, the N-propargyl derivative 12 upon reaction with neat liquid HF at À40 C undergoes intramolecular cyclization to give the fluoro olefin 13(Fig. 4)[8]. Fluorination for the Synthesis of Alkyl Fluorides,Fig.…”

“…[8]. Similar to that of 2-N-benzylglycosyl derivatives, 2-N-allylglycosyl derivatives, for example, N-allyl-D-glucopyranose derivative 8 and N-allyl-D-mannopyranose derivative 10, react with neat HF at relatively low temperature to give the corresponding stereoselectively fluorinated aza-Fluorination for the Synthesis of Alkyl Fluorides,Fig.…”

Synthesis of Monofluoroalkenes: A Leap Forward

“…In 2017, Blériot, Thibaudeau, and co-workers reported the fluorinative cyclization of a 2-(propargylamino)glucopyranose derivative in neat HF to access a bicyclic compound containing a monofluoroalkene (Scheme 92). 108 Scheme 92 Fluorinative cyclization of a 2-(propargylamino)glucopyranose derivative…”