Oleg Lebedev will defend his doctoral thesis "Hydrazine polyanions: different strategies in the synthesis of heterocycles" on 25 August at 12.00 in the faculty of Science and Technology in the University of Tartu. Defence takes place in the Chemicum, Ravila 14a-1021.
Thesis supervisors: Associate professor Uno Mäeorg, PhD, UT Institute of Chemistry
Prof. Dr. Pher G. Andersson, University of Stockholm, Sweden
Oponendid: Ao. Prof. Dr. Michael Widhalm, University of Vienna, Austria
Prof. Dr. Tõnis Kanger, Tallinn University of Technology
Hydrazine moiety can be found in the structures of many well-known dyes, agrochemicals and drugs. In the pharmaceutical industry nitrogen-containing heterocycles take the special place, and C-N bond formation is one of the most employed reaction types. For that reason, synthesis of cyclic hydrazine derivatives, many of which still remain relatively unachievable and unexplored, is of a significant importance. The current dissertation is focused on the synthesis of different types of cyclic hydrazines and introduces a set of new synthetic methods to simplify an access to these compounds.
The central point of the research is formation and alkylation of hydrazine polyanions. It was shown that direct alkylation of hydrazine polyanions with dihalides was applicable for the synthesis of the heterocycles with the N-N bond outside the ring. Polyanion strategy was demonstrated to be an excellent tool for the synthesis of the substrates for ring-closing metathesis from disubstituted hydrazines, thus opening the door to extremely large number of heterocyclic synthetic targets with the N-N bond inside the ring. Also, hydrazine polyanions may be successfully used for a single-step synthesis of aromatic-bridged bis(hydrazines) which may be considered as potential neuroprotective drug candidates. In addition to its practical value, this process may have also a theoretical importance, as it involves an absolutely new reaction type which to the best of our knowledge have never been described before.