Stereoselective synthesis and properties of glycoazobenzene macrocycles through intramolecular glycosylation

Abstract

An intramolecular glycosylation approach has been successfully used to synthesize a series of photoswitchable glycomacrocycles with excellent α-stereoselectivity and interesting photochromic and chiroptical properties.

Sulfur and Azobenzenes, a Profitable Liaison: Straightforward Synthesis of Photoswitchable Thioglycosides with Tunable Properties

“…[9a,b,10] In the same direction, Xie and colleagues reported azobenzene glycomacrolactones, [11] some of which were stereoselectively cyclized by intramolecular glycosylation. [12] In order to maximize the transmission of geometrical information from the azo hinge to the sugar as well as the chirality transfer from the sugar to the molecular switch, a direct connection between both moieties is required. For this purpose, glycosylation of hydroxyazobenzene derivatives is undoubtedly the most obvious reaction in comparison to other approaches such as ester or amide bond formation, urea or thiourea bridging and copper-catalyzed azide-alkyne cyclo-addition (CuAAC).…”

“…More recently, we introduced photoresponsive glycoazobenzene macrocycles, which can change their molecular shape and thus their chiroptical or solubility properties [9a,b,10] . In the same direction, Xie and colleagues reported azobenzene glycomacrolactones, [11] some of which were stereoselectively cyclized by intramolecular glycosylation [12] …”

Sulfur and azobenzenes, a profitable liaison: straightforward synthesis of photoswitchable thioglycosides with tunable properties

“…9a,b In the same direction, J. Xie and colleagues reported azobenzene glycomacrolactones, 10 and some of which were stereoselectively cyclized by intramolecular glycosylation. 11 In order to maximise the transmission of geometrical information from the azo hinge to the sugar as well as the chirality transfer from the sugar to the molecular switch, a straightforward connection between both moieties is required. For this purpose, glycosylation of hydroxyazobenzene derivatives is undoubtedly the most obvious reaction over other approaches such as ester or amide bond formation, urea-or thiourea bridging and copper-catalysed azide-alkyne cycloaddition (CuAAC).…”

Glycomacrocycle-Based Azobenzene Derivatives as Chiral Dopants for Photoresponsive Cholesteric Liquid Crystals

“…The glycomacrocyclic azobenzene derivatives reported by Xie et al are known to undergo a significant conformational change and interesting chiroptical properties upon photoisomerization. [48][49][50] Transfer of chirality from sugar unit to azobenzene could induce certain helicity preferentially, and single molecular chirality level was well switched between E and Z forms with high fatigue resistance and thermal stability. In addition, slight variation on linker length or sugar skeleton may bring significant differences in photoinduced geometrical transition and chiroptical properties.…”

“…In this study, we focused on glycomacrocycles (GMs) consisting of sugar and azobenzene as feasible photoresponsive chiral dopants to achieve higher HTP in the Z -rich state and their significant switching by light irradiation, which has never been utilized to the best of our knowledge. The glycomacrocyclic azobenzene derivatives reported by Xie et al are known to undergo a significant conformational change and interesting chiroptical properties upon photoisomerization. − The transfer of chirality from a sugar unit to azobenzene could induce certain helicity preferentially, and a single molecular chirality level was well switched between E and Z forms with high fatigue resistance and thermal stability. In addition, a slight variation in the linker length or sugar skeleton may bring significant differences in photoinduced geometrical transition and chiroptical properties.…”