Tunable Dimerization and Trimerization of beta-Alkynyl Ketones via Silver Catalysis for Accessing Spiro and Dispiro Compounds Containing 1H-Isochromene

摘要

New silver-catalyzed tunable dimerization and trimerization reactions of beta-alkynyl ketones have been established, enabling multiple C-C bond-forming events to selectively access skeletally diverse spiroisochromenes with generally good yields. The silver-enabled bicycloaddition of beta-alkynyl ketones with water offered hydroxylated spiroisochromenes. Without water, spiroisochromenes with a methylene moiety were obtained through catalytic 6-endo-dig oxo-cyclization/[4+2] cycloaddition cascades by using pyridine as additive whereas employment of 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BiNPO4H) as a Bronsted acid catalyst rendered the unprecedented dispiro trimerization products through double C(sp(3))-H functionalization.