Synthesis of Spiro[benzo[b]thiophene‐2(3H),1′‐cyclopropan]‐3‐ones via Domino Reaction Between Thioaurones and Sulfur Ylides

Abstract

A Cs 2 CO 3 -promoted domino reaction between thioaurones and sulfur ylides was developed. A series of spiro [benzo[b]thiophene-2(3H),1'-cyclopropan]-3-ones were obtained in good-to-high yields. The present domino strategy tolerated both electron-withdrawing and electron-donating groups on both thioaurones and sulfur ylides. The reaction mechanism and the origin of the observed diastereoselectivity were investigated.Scheme 4. The proposed mechanism and the stereoselectivity, along with the computed relative free-energy values (given in square brackets, kcal/mol) by DFT calculations.

Cu-Catalyzed and iodine mediated synthesis of thioaurones via in situ C–S bond generation using xanthate as a sulfur surrogate

“…Also, the reaction between 2a and sulfur ylides using Cs 2 CO 3 was used for its conversion into spiro[benzo [b]thiophene-2(3H),1′-cyclopropan]-3-ones 9 in 90% yield (Scheme 6c). 19 To delve into the reaction mechanism, several control experiments were performed. When the reaction was performed with the radical scavenger BHT (5.0 equiv.)…”

“…Also, the reaction between 2a and sulfur ylides using Cs 2 CO 3 was used for its conversion into spiro[benzo[ b ]thiophene-2(3 H ),1′-cyclopropan]-3-ones 9 in 90% yield (Scheme 6c). 19…”