Organocatalytic Asymmetric Direct C sp 3H Functionalization of Ethers: A Highly Efficient Approach to Chiral Spiroethers

Synthesis of Spirocyclic Ethers by Enantioselective Copper-Catalyzed Carboetherification of Alkenols

Spirocyclic ethers can be found in bioactive compounds. This copper-catalyzed enantioselective alkene carboetherification provides 5,5-, 5,6- and 6,6-spirocyclic products containing fully substituted chiral carbon centers with up to 99 % enantiomeric excess. This reaction features the formation of two rings from acyclic substrates, 1,1-disubstituted alkenols functionalized with either arenes, alkenes, or alkynes, and clearly constitutes a powerful way to synthesize chiral spirocyclic ethers.

Alkyl Ethers as Traceless Hydride Donors in Brønsted Acid Catalyzed Intramolecular Hydrogen Atom Transfer

A new protocol for the deoxygenation of alcohols and the hydrogenation of alkenes under Brønsted acid catalysis has been developed. The method is based on the use of either a benzyl or isopropyl ether as a traceless hydrogen-atom donor, and involves an intramolecular hydride transfer as a key step, which is achieved in a regio- and stereoselective manner.

Direct syntheses of spiro- and fused-hydrofurans by a tunable tandem semipinacol rearrangement/oxa-Michael addition protocol

A highly chemoselective one-pot reaction has been developed involving a tandem semipinacol rearrangement/oxa-Michael addition sequence in which the in situ generated ketol diene intermediate can be transformed specifically to either the spiro- or fused-dihydrofuran products (see scheme). This one-pot tandem reaction represents a general synthetic methodology for the syntheses of the two different kinds of furan derivatives.