Base-mediated formal [4+1] annulation of ortho-hydroxyphenyl substituted para-quinone methides and CF3-imidoyl sulfoxonium ylides to access trifluoroacetimidoyl-substituted 2,3-dihydrobenzofurans

A metal-free [4 + 1] annulation of ortho-hydroxyphenyl substituted para-quinone methides (p-QMs) and CF3-imidoyl sulfoxonium ylides (TFISYs) has been described, producing a series of trifluoroacetimidoyl-substituted 2,3-dihydrobenzofuran derivatives in good to excellent yields with good diastereoselectivities under mild conditions.