Relay Rhodium(I)/Acid Catalysis for Rapid Access to Benzo‐2H‐Pyrans and Benzofurans

Abstract

Relay rhodium(I)/Brønsted acid catalysis for tandem arylation−cyclization reaction was developed. Chemodivergent syntheses of benzo‐2H‐pyrans and benzofurans from propargyl alcohols and ortho‐hydroxylated arylboronic acids were achieved under this relay catalysis system. An ortho‐hydroxy effect on changing the chemoselectivity and reactivity was observed.

A Comprehensive Review on Benzofuran Synthesis Featuring Innovative and Catalytic Strategies

“…Facile and direct formation of C–H and C–X bonds is highly attributed to transition-metal-mediated and directing-group-accompanied bond formation . There is very limited reported work concerning the C–H alkenylation or (DG migration) with 1,3-diynes due to arduous attainment of stereo- and regioselectivity.…”

“…In 2022, Zhu et al 82 carried out the arylation and subsequent cyclization between propargyl alcohols 46 and substituted aryl boronic acids 45 via relay rhodium-mediated catalysis to attain chemodivergent generation of benzofuran skeletons. Their synthetic route was processed by involving toluene sulfonic acid and tetrahydrofuran/water within the reaction medium.…”

“…Facile and direct formation of C–H and C–X bonds is highly attributed to transition-metal-mediated and directing-group-accompanied bond formation. 82 There is very limited reported work concerning the C–H alkenylation or (DG migration) with 1,3-diynes due to arduous attainment of stereo- and regioselectivity. In 2023, Gong et al 83 reported the rhodium-catalyzed novel synthesis of a benzofuran ring by C–H directing group migration between 1,3-diynes 49 and N -benzoxyacetamide 48 .…”

Base-catalyzed addition of silylacetylenes to ketones: a route to protected tertiary propargyl alcohols

“…Propargyl alcohols are ubiquitous building blocks in chemical synthesis, being highly valued for their widespread application as valuable synthetic intermediates or medicinally relevant molecules themselves. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] They participate in a diverse array of transformations, owing this to their multifunctionality, and thereby being the subject of numerous studies. Protected propargyl alcohols can be accessed via well-developed stoichiometric methods, including mainly the use of a combination of propargyl alcohol, chlorosilane and organolithium reagent (Fig.…”

Synthesis of pyrano[3,2-c]quinolones and furo[3,2-c]quinolonesviaacid-catalyzed tandem reaction of 4-hydroxy-1-methylquinolin-2(1H)-one and propargylic alcohols

“…Propargylic alcohols are readily accessible synthetic building blocks in organic synthesis. 16 Over the past few decades, the development of Lewis acid-catalyzed tandem annulations of propargylic alcohols has attracted interests from synthetic chemists, especially for the construction of various heterocyclic skeletons including pyrroles, 17 furans, 18 pyrans, 19 carbazoles, 20 quinolines, 21 and tetrahydro-β-carbolines. 22 We herein describe the development of acid-catalyzed formal [3 + 3]/[3 + 2] cascade annulation processes for the construction of pyrano[3,2- c ]quinolone/furo[3,2- c ]quinolone derivatives from 4-hydroxy-1-methylquinoline-2(1 H )-one and propargylic alcohols ( Scheme 1b ).…”