Regioselective Construction of Indene Skeletons by Palladium‐Catalyzed Annulation of Alkynylborates with o‐Iodophenyl Ketones

Abstract

A palladium‐catalyzed annulation reaction of alkynylborates with o‐iodophenyl ketones to form indenes is described. Highly substituted indene skeletons are efficiently constructed with site‐specific installation of the substituents.

Regioselective 5‐endo‐dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo‐substituted Indenes and Cyclopenta‐Fused Arenes

“…The carbo‐ and heterocyclic compounds constitutes an important class due to their presence in a large number of drug molecules, which acquire a remarkable pharmaceutical activity . For instance, indene skeleton with an exo ‐alkylidene moiety is embedded in Sulindac ( 1 ), which is a non‐steroidal anti‐inflammatory drug, Dimethindene ( 2 ), an oral antihistamine agent, and Donepezil ( 3 ), an anti‐Alzheimer drug (Figure ) . In addition to these commercial medicines, indenes are the structural constituent of group IV metallocene bound catalysts, which are used for olefin polymerization …”

Synthesis of Isomerically Pure (Z)-Alkenes from Terminal Alkynes and Terminal Alkenes: Silver-Catalyzed Hydroalkylation of Alkynes

“…We reasoned that in the 1,2-metalate shift described by Brown, the Brønsted acid could be replaced by a cationic complex of a coinage metal (Scheme b). The 1,2-metalate shift promoted by π-acid coordination , to the alkyne has been shown to require antiperiplanar orientation of the π-acid and the migrating group and would allow exclusive formation of the Z -alkene product. Furthermore, the coinage metal complex could be delivered in the form of a metal acetylide that would replace the lithium acetylide used in the reaction sequence described by Brown.…”