تحضير بيرفلورو اثيل ترايازولات جديدة مشتقة من سكر D. كالكتوز باستخدام كيمياء النَقرّة ودراسة بعض دوالها الثيرموديناميكية

Synthesis of New Perfluoroethyl Triazoles Derived from α-D-Galactose sugar Via Click Chemistry and Study Some of their Thermodynamic Functions

This work includes synthesis of new perfluoro triazole starting from D-galactose. Firstly, 1,2:3,4-di-O-isopropylidene-α-D-galactose (66) was synthesized by the reaction of D- galactose, acetone and sulfuric acid in presence ZnCl₂ then the work was been divided into two lines.

     The first line describes: Williamson etherfication of compound (66) with propargyl bromide in basic media gave the terminal alkyne derivative  6-O-prop-2-ynyl-1,2:3,4-di-O-isopropylidene-α-D-galactose (67).

While the second one describes the synthesis of 1,2:3,4-di-O-isopropylidene-α-D-galactose-6-O-triflate (68) with good leaving group from the esterfication of compound (66) by trifluoromethanesulfonic anhydride in dry pyridine. The treatment of derivative (68) with sodium azide afforded 6-azido-6-deoxy-1,2:3,4-di-O-isopropylidene-α-D-galactose (69) in good yield.

The derivatives (67) and (69) have been utilized to synthesize of the targeted perfluoro triazoles via Cu (I) catalyst 1,3-dipolarcycloaddition: the reaction of  derivative (67) with azides as active group and ethyl spacer with different perfluoro chain, afforded triazole derivatives (74-76).

While the reaction of compound (69) with perfluoroethyl propargyl ethers (71-73) using the same Cu (I) catalyst conditions yielded the perfluorotriazoles (77-79).

   All the synthesized compounds have been characterized by spectroscopic methods [FT-IR; ¹H and ¹³C NMR], while the targeted compounds (74-79) have been characterized by [FT-IR; ¹H, ¹³C NMR, HSQC, COSY and Mass] spectroscopic methods. The thermodynamic functions (∆H, ∆G and ∆S) of compounds (74-79) have been studied using DSC instrument, thermodynamics calculations showed increasing the enthalpy values corresponding with increasing the perfluoro chain which caused by the rigidity of perfluoro chain reason the helical shape.