Solvent Effects on the [3+2] Cycloaddition of 2-Furfural Oxime and Ethyl Propiolate: Unexpected Change in Regioselectivity

• DOI: 10.12691/wjoc-5-1-2
• Publication Date: 2017-07-06
• Authors: Promi Rahman; Amy Glanzer; Jaffarguriqbal Singh; Nanette M. Wachter; Jonathan Rhoad; Richard W. Denton
• Keywords: Dichloromethane

The effect of solvents on the 1,3-dipolar cyclization reaction between ethyl propiolate and 2-furfuryl nitrile oxide was studied in various organic solvents. As expected, major product ethyl-3-(2-furanyl)-5-carboxylate. relative ratio 3,5- to 3,4- disubstituted isoxazoles dichloromethane, toluene, ethanol dimethyl sulfoxide were 3.4, 2.0, 1.9 1.5 respectively. Experimental regioselectivity found be dissimilar density functional theory predictions.