We present here a rhodium-catalyzed
oxidative three-point double
annulation of enaminones with propargylic alcohols via a C–H
and a C–N bond activation to access arylnaphthalene-based lignan
derivatives. The key step in the reaction is the regioselective insertion
of propargylic alcohol into the rhoda-cycle, a result of hydroxyl
rhodium coordination. Necessary control experiments and KIE studies
were conducted to determine the mechanism.
Metal catalyzed cyclizative cross coupling reactions attract enormous attention with their unique cascade nature. We demonstrate herein, a dual-cyclizative coupling of ynone oxime ethers with acrylamides for the synthesis of...
We disclose herein a Rh(III)-catalyzed migratory three-point double annulation of o-alkenyl phenols with propargyl alcohols for de novo construction of naphtho furan derivatives in a regio-and chemoselective manner. The protocol orchestrates two new rings with four new bonds in one operation without the need for any additive. Necessary labeled and control experiments are conducted to elucidate the reaction mechanism. A tertiary hydroxyl group is found to be crucial both for controlling the regioselective insertion of alkyne through chelation with rhodium to form a key spiro cyclic intermediate and for forcing ring expansion via unusual and selective olefin reshuffling, apart from forming an extra (furan) ring. The protocol is scalable and shows tolerance for late stage functionalization of natural products.
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