Synthesis of 2(5H)-Furanone Derivatives with Symmetrical and Unsymmetrical Bis-1,2,3-triazole Structure

Abstract

SUPPORTING INFORMATION Full experimental detail(Characterization spectra of 32 new compounds 2a-2h, 3a-3h, 5aa-5bh. For each compound, the former is 1 H NMR, and the latter is 13 C NMR.) 2 EXPERIMENTAL GeneralMelting points were determined on an X-5 digital melting points apparatus and were uncorrected. Infrared spectra were recorded on a Bruker Vector 33 FT-IR instrument by liquid film method in the absorption range of 4000-400 cm -1 . 1 H and 13 C NMR spectra were obtained in CDCl 3 on a Varian DRX-400 MHz spectrometer and tetramethylsilane (TMS) was used as an internal standard. UV absorption peaks were measured by Shimazu UV-2550 ultraviolet absorption detector with dichloromethane as a solvent. Optical rotations were determined with an Autopol IV polarimeter in CH 2 Cl 2 in a 10 cm cell. Elemental analysis was performed on a Thermo Flashea TM 112 elemental analyzer. The mass spectra (MS) were recorded on Thermo LCQ DECA XP MAX mass spectrometer.All reagents and solvents were commercially avail-able and used as received. The intermediates N-[(5S)-5-alkoxy-2(5H)-furanonyl] amino acid propargyl esters 1 were prepared according to the literature. [31] General procedure for the synthesis of target compounds 2 A flame-dried flask was charged with 1 mmol N-[(5S)-5-alkoxy-2(5H)-furanonyl] amino acid propargyl esters 1, 0.5 mmol 1,4-diazidobutane, [42] 0.05 mmol Cu(OAc) 2 •H 2 O and 0.1 mmol Cu in CH 3 CN (5 mL). The mixture was stirred at room temperature under N 2 atmosphere and monitored by TLC. Once the reaction was completed (about 16 h), the reaction mixture was quenched with a saturated aqueous solution of NH 4 Cl (20 mL) and extracted with ethyl acetate (3×30 mL). The organic layer was dried over MgSO 4 , and concentrated in vacuo. The residue was purified by column chromatography using the mixture of petroleum ether and ethyl acetate as eluent to yield the desired compounds 2a-2h in 41-56% isolated yields.