Indium(III) chloride-catalyzed Mukaiyama-Michael addition: synthesis of 2,6-anti-tetrahydropyrans

In the presence of a catalytic amount of indium(III) chloride (InCl3), silyl enol ethers react with dihydropyranones at ambient temperature via Mukaiyama-Michael addition to afford the corresponding 2,6-anti-tetrahydropyran adducts in moderate to good yields. This simple and mild method proceeds under neat conditions and involves simple aqueous work-up. Indium(III) chloride can be recovered and reused without significant decrease in reactivity.