3-Nitrobenzo[b]furan and 1-diethylaminopropyne react thermally at 5–10°C to give a 1:1 addition product ( ) in which one of the oxygen atoms of the nitro group is transferred to C-1 of the acetylene. The structure of the benzofuro[3,2-c]isoxazole ( ) has been determined by X-ray crystallography.
de Wit, A. D., Trompenaars, W. P., Reinhoudt, D., Harkema, S., & van Hummel, G. J. (1980). Reduction of nitro groups by ynamines; synthesis and x-ray crystal structure of n,n-diethyl-3,3a-dihydro-3-methylbenzofuro[3,2-c]isoxazole-3-carboxamide. Tetrahedron letters, 21(18), 1779-1780. https://doi.org/10.1016/S0040-4039(00)77836-1