musings on music and life

November 13, 2014

amphoteros

Filed under: Chemistry, Uncategorized — Tags: — sankirnam @ 8:19 pm

I’ve been following Prof. Andrei Yudin’s blog for a while, and wanted to mention it here since he recently discussed an article by Prof. Karl Christe (one of my committee members). Prof. Yudin got his PhD with my advisor approximately 20 years ago, and after completing a postdoc with Prof. K. Barry Sharpless (Scripps), became a very successful professor at the University of Toronto. He initially did some interesting work with fluorinated BINAP and BINOL complexes and investigated their catalytic activity. However, his real claim to fame is his discovery of the rich chemistry of aziridine aldehydes.

One of the long-standing challenges in organic chemistry is the synthesis of compounds that contain complementary reactive groups in the same molecule. One example of this type of molecule is an unprotected amino aldehyde. Amines and aldehydes readily condense to form imines and/or hemiaminals depending on the conditions, and that is why one will never see small molecules containing free -NH2 and -CHO groups in the same structure. Prof. Andy Myers (Harvard) has synthesized N- and C– protected amino aldehydes as precursors for the in situ generation of free amino aldehydes.

Prof. Yudin elegantly demonstrated that if the amine is in the form of an aziridine (3-membered ring), then there is a kinetic barrier for imine formation, and thus unprotected (-NH) amines can exist along with an aldehyde functionality in the same molecule. These aziridine aldehydes can be accessed from DIBAL-H reduction of aziridine esters. They exist as homodimers and it is possible to chemoselectively access amine or aldehyde reactivity with the appropriate reagents and conditions.

Prof. Yudin continues his work with other intriguing amphoteric molecules and has also demonstrated novel applications for these new compounds, including their use towards the synthesis of cyclic peptides.

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