Pd(II)-Catalyzed Tandem Cycloannulative-Alkenylation of <i>o</i>-Alkynyl-Phenols/Anilines with (<i>E</i>)-β-Iodovinyl Sulfones: A Direct Strategy To Construct 3-(Vinyl sulfonyl)benzoheterole Derivatives
Raju Jannapu Reddy, Nunavath Sharadha, Gamidi Rama Krishna
Abstract
Benzoheteroles and vinyl sulfones are the most promising pharmaceutical relevance motifs, yet the hybrid analogues of these scaffolds still need to be explored. We report herein a general and highly efficient Pd(OAc) 2 -catalyzed intramolecular cyclization and vinylation of o -alkynylphenols/ o -alkynylanilines with ( E )-β-iodovinyl sulfones under mild reaction conditions. A direct C(sp 2 )–C(sp 2 ) cross-coupling is enabled for the diversity-oriented synthesis of vinyl sulfone-tethered benzofurans and indoles in good to high yields with excellent stereoselectivity. Notably, this tandem process was consistent at the gram scale, and in situ, generation of 2-(phenylethynyl)phenol has also been utilized in a scalable synthesis. Late-stage synthetic transformations were also further explored, including isomerization and desulfonylative-sulfenylation. Moreover, several control experiments were accomplished, and we proposed a plausible mechanism based on existing experimental results.