|MIT Department: Chemistry
Faculty Mentor: Prof. Christopher Cummins
Undergraduate Institution: Williams College
My name is Brian Valladares, and I am from Chicago, Illinois. Currently, I am a rising senior at Williams College studying Chemistry with a concentration in Public Health. My research interests focus on developing novel molecules with biological applications that can have a larger impact in society. I plan on pursuing a PhD in organic chemistry with the goal of becoming a medicinal chemist. This summer I conducted research at MIT under Professor Christopher Cummins focusing on developing N-Heterocyclic Iminophosphazenes (NHIPs) as a novel subclass of superbases. Outside of the lab, I enjoy playing soccer, exploring new restaurants, and listening to music.
The Synthesis and Characterization of N-Heterocyclic Iminophosphazenes (NHIPz), a Novel Subclass of Superbases
Brian Valladares1, Keita Tanaka2 and Christopher C. Cummins2
1Department of Chemistry, Williams College
2Department of Chemistry, Massachusetts Institute of Technology
By definition, superbases have a basicity greater than a Proton-Sponge or a pKBH+ greater than 18.6 in acetonitrile. Superbases are known for their ability to access pronucleophiles with high pKas, which drives base catalyzed reactions that normally would not be favorable. They commonly suffer from side reactions due to their high reactivities. Recently, designer superbases have enabled highly enantioselective reactions, offering wide applications in the drug discovery process. This work endeavors to introduce a novel subclass of superbases, N-Heterocyclic Iminophosphazene (NHIPz). This synthesis was achieved by the key synthetic step of a 1,3-dipolar cycloaddition of alkynes with azophosphine (ArN=N–P(NMe2)2). In terms of structure, amino substituents on the phosphorus of the NHIPz parallel well-known phosphazene superbases. The cyclic nature of NHIPz provides an added rigidity that has not been previously reported, while improving the selectivity of the superbase in reaction development. Future works aspire to apply NHIPz to known superbase-mediated or catalyzed reactions and to compare their reactivities and selectivities.