News & Events

Symone Alexander

Posted on November 11, 2020


Date - November 11, 2020
1:00 pm - 2:00 pm


Title: Diastereoselective Cyclization of Lactones via Brønsted Acid Catalysis


Chiral molecules play a vital role in biologically effective drugs and a majority of
pharmaceutical companies seek to isolate the enantiomers of molecules in drug design.
Enantioselective synthesis can be a valuable tool in the creating single enantiomers. A
particular technique for synthesizing enantiomers is desymmetrization, which a prochiral
molecule losses its symmetry elements through a reaction. In this work, desymmetrization will
be done utilizing a diester with a Brønsted acid catalyst, to achieve mild reaction conditions for
cyclization. Providing these mild conditions decreases the chances of side reactions that can
happen in harsher reaction conditions which can hinder enantioselectivity.

This thesis describes the expansion of previous work in the Petersen Group, to the
synthesis of six-membered lactones with multiple stereocenters. Previous work utilized prochiral
nitrile compounds to synthesize -lactones, and this work provides the results of diastereo- and
enantioselective desymmetrizations with malonic esters. Once cyclization was achieved the
reaction was optimized by varying the achiral Brønsted acid catalyst used, temperature, and
solvents. After optimization of our first substrate containing a bulky phenyl group, a second less
bulky alkylating agent was used to examine the diastereoselectivity of this new multicentered