Formation of furofurans from tetraacetylethylene. Molecular and crystal structure of a spiro[furan-2(5<i>H</i>),2′(3′<i>H</i>)-furo[2,3-<i>b</i>]furan]

Abstract

Dimerization of tetraacetylethylene (TAE) 1 has led to a spiro[furan-2(5H),2′(3′H)-furo[2,3-b]furan], whose structure was established by X-ray analysis. The trend of TAE to furan ring closure was confirmed by the reaction with ethyl vinyl ether, where the first product of the reaction, the pyran adduct 8, smoothly rearranged to a furo[2,3-b]furan derivative 9.