Intermolecular Sonogashira Coupling and Intramolecular 5-Exo-dig Cycloisomerization Cascade: A One-Pot Pathway for Accessing (3-Benzylbenzofuran-2-yl)(phenyl)methanones

Abstract

Herein, we present an efficient and straightforward strategy enabling access to 2,3-disubstituted benzo­[b]­furans. The whole synthetic process proceeds via a domino intermolecular Sonogashira coupling of 2-(2-bromophenoxy)-1-phenylethan-1-ones/alkyl 2-(2-bromophenoxy)­acetates/2-(2-bromophenoxy)­acetonitrile/1-(2-bromophenoxy)­propan-2-one with terminal acetylenes followed by an intramolecular carbanion-yne cyclization in a 5-exo-dig manner and subsequent double-bond isomerization. Notably, two C–C bonds have been constructed in a one-pot manner and a wide variety of (3-benzylbenzofuran-2-yl)­(phenyl)­methanones were accomplished with good functional group tolerance.

Recent Expedition inPd‐CatalyzedSonogashira Coupling and Related Processes†

“…[ 49 ] A similar reaction protocol was used in the intermolecular Sonogashira coupling and intramolecular 5‐ exo ‐ dig cycloisomerization cascade reaction to obtain benzofuran derivatives. [ 50 ] The Pd(OAc) 2 / Xanthpos catalyst system was further used in the on‐DNA Sonogashira coupling with HP‐ArOFs in 2019. [ 51 ]…”

Palladium-Catalyzed Acylation Strategies and Their Applications Towards Biologically Relevant Products

“…[1][2][3][4][5][6][7][8][9][10][11] Specifically, palladium metal catalysis has opened new avenues via the construction of C-C/C-X bond. [12][13][14][15][16][17][18][19][20][21][22][23][24] Various C-H functionalization strategies through directing and non-directing group pathways have been intensively established in recent years. [25][26][27][28][29][30][31][32][33] In addition, palladium-catalyzed coupling strategies have been featured as the key transformations in successful syntheses of natural products and pharmaceutically active molecules.…”

Gold self-relay catalysis enabling annulative oxygenation of propargylic alcohols with O-nucleophiles

“…6 Due to their potential utilities, there has been growing interest in developing reliable and versatile methods for constructing such scaffolds, and a number of synthetic approaches have been documented in recent years. 7 Among the many strategies toward 2,3-disubstituted benzo[ b ]furans, one of the most common and widely used methods is based on transition metal catalyzed annulative C–H functionalization of phenols (Scheme 1a). 8 Other popular approaches employ base-promoted or transition metal catalyzed intramolecular cyclization of ortho -alkynylaryl alkyl ethers 9 or 2-alkynylphenols (Scheme 1b).…”