In memory of Prof. Dr. Rolf Huisgen
An enantioselective hetero-Diels–Alder reaction of alkylidene oxindoles and 2-aza-3-silyloxy-1,3-butadienes, catalyzed by divalent transition metal complexes with N,N′-dioxide ligands offered an efficient access to natural-product-based 3,3′-piperidinoyl spirooxindole class of small molecules. exo-Cycloadducts formed via stereospecific cycloaddition with Z-olefin displayed potent activity in modulation of hedgehog pathway.
Key words
asymmetric synthesis - hetero-Diels–Alder reaction - spirooxindoles - natural products - hedgehog inhibitors