Synthesis of Fulvene Vinyl Ethers by Gold Catalysis.
Alexander AhrensJulia SchwarzDanilo M LustosaRaheleh PourkavehMarvin HoffmannFrank RomingerMatthias RudolphAndreas DreuwA Stephen K HashmiPublished in: Chemistry (Weinheim an der Bergstrasse, Germany) (2020)
Gold-catalyzed cyclization of 1,5-diynes with ketones as reagents and solvent provides diversely substituted vinyl ethers under mild conditions. The regioselectivity of such gold-catalyzed cyclizations is usually controlled by the scaffold of the diyne. Herein, we report the first solvent-controlled switching of regioselectivity from a 6-endo-dig- to 5-endo-dig-cyclization in these transformations, providing fulvene derivatives. With respect to the functional-group tolerance, aryl fluorides, chlorides, bromides, and ethers are tolerated. Furthermore, the mechanism and selectivity are put to scrutiny by experimental studies and a thermodynamic analysis of the product. Additionally, 6-(vinyloxy)fulvenes are a hitherto unknown class of compounds. Their reactivity is briefly evaluated, to give insights into their potential applications.