RUI: Asymmetric catalytic hydroamination of aminoallenes by chiral tantalum cyclopentadienyl-amide-alkoxide complexes

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The Chemical Catalysis Program supports Professor Adam R. Johnson at Harvey Mudd College who will examine enantioselective hydroamination catalysis and stereoselective polymerization of lactide, which are two areas of significant current interest. The proposed research will examine the hydroamination reaction, which is the addition of a nitrogen-hydrogen bond across a carbon-carbon multiple bond. The highly atom-economical method produces substituted amines that are valuable synthetic targets. A number of metals catalyze this reaction but there are no general methods for it. The asymmetric hydroamination of aminoallenes using titanium complexes of bidentate aminoalcohol ligands gives good regioselectivity, but poor stereoselectivity. The corresponding tantalum complexes have recently been shown to be more stereoselective. The PI and his coworkers will synthesize novel chiral ligands tethered to a chiral amino-alcohol and rapidly screen them, synthesize and study titanium and tantalum complexes with these chiral ligands, and perform catalytic hydroaminations with tethered and untethered ligands. The chiral amino-alcohol complexes will also be used to polymerize the biologically derived monomer, lactide. As a biodegradable polymer based on a renewable feedstock, the development of efficient catalysts for the synthesis of polylactide with varying tacticity is of great importance. If successful, both areas of research will have a transformative impact.With the support of the Chemical Catalysis Program in the Chemistry Division at the National Science Foundation, Dr. Adam R. Johnson's continued research on hydroamination will have an impact on teaching at the frontiers of organometallic chemistry and will extend to a wide community of inorganic chemistry educators. The results from this research will affect Professor Johnson's teaching of inorganic and organometallic chemistry at Harvey Mudd College and his participation in the NSF-funded VIPEr project (www.ionicviper.org), an on online teaching and networking site for inorganic chemistry. Undergraduate students will have an opportunity to examine modern problems in synthetic organometallic chemistry, synthesize and purify the ligands and complexes, grow crystals, and perform the catalytic reactions. Students will gain experience in creative problem solving and teamwork, and will present their research results both locally and at a national American Chemical Society Meeting.