Bi(OTf)₃‐Mediated (4+1) Annulation of α‐Sulfonyl o‐Hydroxyacetophenones with α‐Hydroxy Arylketones to Access Sulfonyl 2‐Aroylbenzofurans

Abstract

In this paper, a high-yield, facile route for the scalable synthesis of sulfonyl 2-aroylbenzofurans via a Bi(OTf) 3 -mediated intermolecular double cyclocondensation of α-sulfonyl o-hydroxyacetophenones with substituted α-hydroxy arylketones under mild open-vessel reaction conditions is described. In the overall reaction, water is generated as the only byproduct. Various metal triflate-promoted reactions and conditions are investigated for the efficient one-pot (4 + 1) annulation reaction.

Construction of Sulfonyl Dibenzofused Medium‐Size Oxacycles via Bi(OTf)3‐Catalyzed Friedel‐Crafts‐Type Annulation

“…To the best of our knowledge, flexible methods for synthesizing sulfonyl‐containing dibenzofused medium‐size rings have not been reported so far. Based on our recent experiences with regard to the one‐pot tandem Bi(OTf) 3 ‐catalyzed synthesis of sulfonyl‐containing benzofused skeletons (i. e., 1‐aryl isoquinolinones, [9a] 2‐aroyl benzofurans, [9b] dibenzooxabicyclo[3.3.1]nonanes), [9c] we developed a Bi(OTf) 3 ‐catalyzed approach to achieve a series of versatile 4 using two starting o ‐hydroxy acetophenones 2 and benzofused cycloethers 3 in MeNO 2 at 60 °C under the open‐vessel reaction condition. In the sequential cyclization procedure, 4 could be constructed via cascade single‐bond formation of carbon‐carbon and carbon‐oxygen single bonds.…”

Access to 2‐Sulfonyl‐4‐arylphenols and 2,6‐Bis‐sulfonyl 5‐Aryl‐4‐arylidene‐2‐cyclohexenones via Metal Triflates‐Catalyzed Domino Cyclocondensation of 1,3‐Bis‐sulfonylacetones and 3‐Arylacroleins

“…Among domino routes, the development of adopting cyclocondensation as the key approach has been attracting considerable attention [2] . Recently, we utilized domino cyclocondensation to explore the synthesis of sulfonyl‐containing molecules, including 2‐aroylbenzofuran, [3a] benzo[ c ]xanthen‐7‐one, [3b] and dibenzooxabicyclo[3.3.1]nonane, [3c] based on the transition metal‐promoted functionalization of α‐sulfonyl o ‐hydroxyacetophenone under a rapid annulation process. Based on the previous results on synthesis, we focused on applying 1,3‐bis‐sulfonylacetone as a new starting substrate for constructing sulfonyl‐conjugated frameworks via cascade process.…”