Synthesis of Diastereoenriched 1-Indanones via Double-Base Cooperatively Promoted 1,4-Oxo-Migration/Cyclization of β-Alkynyl Ketones.

A double-base copromoted 1,4-oxo-migration/cyclization cascade of β-alkynyl ketones was reported, enabling to form a range of functionalized 1-indanones with moderate to good yields and high diastereoselectivity in the presence of t-BuOK as a Brønsted base and N,N'-dimethylethanediamine (DMEDA) as a Lewis base. Some of these 1-indanones were successfully transformed into 2-haloethyl benzoates with one all-carbon quaternary stereocenter by 1,2-dichloroethane (DCE) or 1,2-dibromoethane (DBE) as both a reactant and a reaction media. This method also features high atomic utilization (100%), high diastereoselectivity, and mild reaction conditions.