Dihydropyridazine Derivatives with Cyclopenta??, Benzo??, Furo??, Thiopyrano??and Pyrido??Annulation

M Penning, J Christoffers

Index: Penning, Miriam; Christoffers, Jens European Journal of Organic Chemistry, 2013 , # 2 p. 389 - 400

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Citation Number: 2

Abstract

Abstract Regioisomeric [c] annulated pyridazines were prepared from arylhydrazines and carbocyclic or heterocyclic β-oxo esters with an α-phenacetyl moiety. With AcOH/EtOH, the hydrazones were preferentially formed at the endocyclic ketone, which are further cyclized with trifluoroacetic acid (TFA)/CH 2 Cl 2 to give 2, 4a-dihydropyridazines. Use of TFA/CH 2 Cl 2 led hydrazones at the exocyclic benzoyl group, which reacted further to give 1, 4- ...