Host-Guest Approach To Combo Catalysis

With the use of a supramolecular host-guest framework, researchers at the University of California, Berkeley, have developed a protocol for bringing together organometallic catalysts and enzymes to mediate one-pot tandem reactions (Nat. Chem., DOI: 10.1038/nchem.1531). The work highlights a strategy for carrying out chemical transformations not possible with either type of catalyst alone while also preventing adverse interactions between the catalysts and extending their lifetimes. Z. Jane Wang, F. Dean Toste, and coworkers previously found that sheltering a gold complex in a Ga₄L₆ framework, where L is a benzoyl-naphthalene ligand, yields a host-guest species that catalyzes allene alkoxylation more actively than does the free gold complex. The team has now shown that Au(I) or Ru(III) host-guest species can be paired with esterases or lipases to mediate multistep reactions. For example, the researchers used an enzyme to convert an allenic acetate to the corresponding alcohol and subsequently used a sheltered gold catalyst to cyclize the alcohol to form a substituted tetrahydrofuran.