Base-Promoted Formal (2+1) Cycloaddition of Benzofuran-Derived Oxadienes with Bromomalonates.

Notably, substrates B 1s b and B 1t b bearing a heteroaryl group and a naphthyl group, respectively, also served as suitable reaction partners, participating in the formal (2+1) cycloaddition to provide the benzofuranone-based spirocyclopropanes B 3sa b and B 3ta b , respectively (entries 19 and 20). [15][16][24][32][33] As shown in Scheme 1a, benzofuran-derived oxadienes are widely used as two-atom building blocks in highly diastereoselective (2+3) cycloadditions. Moreover, I ortho i -, I meta i - and I para i -substituted phenyl groups were found to be suitable R SP 1 sp groups for the benzofuran-derived oxadienes B 1 b , affording the target products B 3fa b - B ra b in overall high yields and moderate to good diastereoselectivities (entries 6-18). Keywords: (2+1) cycloaddition; diastereoselectivity; benzofurans; oxadienes; bromomalonates; spiro compounds EN (2+1) cycloaddition diastereoselectivity benzofurans oxadienes bromomalonates spiro compounds 1704 1708 5 08/18/23 20230901 NES 230901 Graph Benzofuran is an important class of oxygen-containing heterocycles that frequently occur as substructures in natural products and synthetic compounds. [Extracted from the article]