Synthesis
General procedure for the synthesis of ethyl tetrahydrofuran-2-acetate from tetrahydrofuran and ethyl diazoacetate: first, methyl phenyl diacetate was prepared by the reaction of methyl phenylacetate with p-acetamidobenzenesulfonyl azide. The dried non-homogeneous catalyst (containing 0.02 mmol Cu) was suspended in anhydrous tetrahydrofuran (10 mL containing 100 mg of n-decane as internal standard) and heated to reflux under inert atmosphere. Anhydrous tetrahydrofuran (10 mL) solution of diazo compounds (1 mmol) was slowly added over a period of 2 hours using a syringe pump. After the addition was completed, the reaction mixture was continued to be stirred under reflux conditions for 30 min. Subsequently, the catalyst was removed by filtration and washed with tetrahydrofuran (5 mL). Yield and stereoselectivity were determined by gas chromatography (GC). After addition of diazo compounds and heating at reflux for 2 h, the presence of active copper substances in solution was detected by analytical tests. After drying the catalyst under vacuum, it can be reused under the same conditions. Enantioselectivity was determined by high performance liquid chromatography (HPLC) when the reaction was carried out in the presence of chiral ligands.
References
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