337 REGIOCONTROLLED 1,3-DIPOLAR CYCLOADDITIONS OF NITRILE IMINES WITH ACETYLENES AND ,-UNSATURATED SYSTEMS: SYNTHESIS OF POLYSUBSTITUTED AND RING FUSED PYRAZOLES WITH PHARMACEUTICAL ACTIVITY DOI: http://dx.medra.org/10.17374/targets.2017.20.337 Giulio Bertuzzi, Mariafrancesca Fochi and Mauro Comes Franchini Department of Industrial Chemistry “Toso Montanari”, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy (e-mail:
[email protected]) Abstract. 1,3-Dipolar cycloadditions of nitrile imines with functionalised acetylenes and ,-unsaturated systems of various sizes have been studied. After cycloaddition, mono- and ring-fused pyrazoles have been obtained. Computational studies allowed a theoretical description of the observed reactivity, in agreement with the experimentally observed regio-chemistry. Selected targeted structures for medicinal applications have been synthetized and in vitro cytotoxicity showed that these pyrazoles can be considered powerful lead compounds for further medicinally relevant targets development. Contents 1. Introduction 2. 1,3-Dipolar cycloaddition of nitrile imines with acetylenes 2.1. 1,3-Dipolar cycloaddition of nitrile imines with activated acetylenes: regiocontrolled synthesis of 4- and 5-substituted pyrazoles 2.2. 1,3-Dipolar cycloaddition with sulphur-based acetylenes: regiocontrolled synthesis of thieno[2,3- c]pyrazoles 2.3. 1,3-Dipolar cycloaddition with ynamide tert-butyl N-ethynyl-N-phenylcarbamate: experimental and theoretical investigation 3. 1,3-Dipolar cycloaddition of nitrile imines with cyclic dipolarophiles 3.1. 1,3-Dipolar cycloaddition of nitrile imines with α,β-unsaturated ketones: regiocontrolled synthesis of ring-fused pyrazoles 3.2. 1,3-Dipolar cycloaddition of nitrile imines with α,β-unsaturated lactones, thiolactones and lactams: regiocontrolled synthesis of ring-fused pyrazoles 4.