Download Chris Sprout”s

Chris Sprout”s
Burak, sorry it took me so long
My research project falls in the general category of asymmetric catalysis. I
have been synthesizing amino acid based based ligands in a modular fashion. The
ligands are used in the dialkylzinc addition to aldehydes. I have found that
Me2Zn, in the presence of our ligands, adds to 2-naphthaldehyde,
4-Cl-benzaldehyde, and benzaldehyde in 86%, 84%, and 81% enantiomeric excess
(ee) respectively.
Inspiration for this project stems from the need for high-throughput screening
methods to determine ee of large libraries of compounds. Combinatorial
synthesis has aided pharmaceutical companies in the discovery of better drugs.
We believe that utilization of parallel combinatorial libraries is the best way
to find better catalysts. By designing a novel class of ligands with easily
diversified subunits the power of combinatorial chemistry can be realized. The
problem arises when one analyzes 1000+ products for ee by traditional chiral
HPLC or GC. The answer involves a fast high-throughput screening methodology.
The ligands are designed to mimic the successful B-amino alcohols. The idea
is to use an amide group which has a similar pka to an alcohol. We term these
new ligands B-amino amides. The synthesis involves a simple HBTU coupling of a
Boc-protected amino acid with a commercially available
N,N-dialkylethylenediamine. Further diversification involves removal of the Boc
group and either capping with an acid chloride or a chloroformate. Other amino
acids could also be added to build in more stereocenters into the ligands.