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Title: Synthesis of 1,2,4 oxadiazol-5-imine, 1,2,4-triazol-3-imine and derivatives : a substituted cyanamide-based strategy for heterocycle synthesis
Author: Bhat, Shreesha V.
ISNI:       0000 0004 6422 1072
Awarding Body: University of Lincoln
Current Institution: University of Lincoln
Date of Award: 2017
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Considering the importance of nitrogen-rich heterocycles in drug discovery, a novel strategy towards heterocycle synthesis was envisioned using cyanamide chemistry. Synthesis which involve mild conditions, avoids multi-step sequence and non-toxic reagents are desirable for generation of large combinatorial libraries of drug molecules. We envisaged that the NCN linkage of the cyanamide as well as the concomitant use of the nucleo-and electrophilic centres of the cyanamide could provide a novel synthetic route towards nitrogen heterocycles. The first part (Ch-2) constitute the bulk of the thesis and it focuses on the generation of cyanamide ion and its cyclisative capture with a 1,3-dipole – nitrile oxide in situ. The cycloadduct -1,2,4-oxadiazol-5(4H)-imine was obtained in good yields, which was further transformed into pharmacologically important cores like oxadiazolone and amidines. A library of the different heterocyclic cores was generated, which tolerated a wide variety of functional groups in good to excellent yields. In the second part (Ch-3), we developed a novel protocol for the synthesis of 1,2,4-triazol-3-imine via a formal 1,3-dipolar cycloaddition of in situ generated nitrile imines and cyanamide ion. Further hydrolysis furnished with 1,2,4-triazol-3-one, which is an important core from medicinal chemistry point of view. The concomitant generation and reaction of two reactive species- 1,3-dipoles and cyanamide ion was achieved in a single pot in situ to provide a route towards novel and pharmaceutically important heterocyclic cores. The present work provides a platform for the development of cyanamide derivatives as a ‘single-reagent—diverse-scaffolds’ strategy for time efficient library delivery of structurally diverse molecules.
Supervisor: Sharma, Pallavi Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: F151 Pharmaceutical Chemistry