BF3·Et2O-assisted synthesis of sulfinylated spiro[5.5]trienones from biaryl ynones.

Sulfinyls are valuable structural moieties used for developing synthetically new pharmaceuticals and agrochemicals. Herein, we disclose a straightforward synthesis of sulfinylated spiro[5.5]trienones proceeding via an unprecedented BF3·Et2O-promoted spirocyclization of biaryl ynones. The availability of relatively inexpensive BF3·Et2O to carry out transformations on a bulk scale along with its further application towards the synthesis of dibenzocyclohepten-5-ones delivers a unique opportunity to deploy it in various synthetic directions.