Highly Enantioselective Copper-Catalyzed Alkylation of β-Ketoesters and Subsequent Cyclization to Spirolactones/Bi-spirolactones

Cu-catalyzed enantioselective alkylation of β-ketoesters
using alcohols for in situ preparation of alkylating
reagents is reported. A number of functionalized β-ketoesters
containing a quaternary carbon stereocenter are obtained with up to
99% ee. The alkylation products derived from 2-substituted allylic
alcohols or their corresponding iodides can then be converted to spirolactones,
bi-spirolactones, and related chiral target products.