title: Divergent Reactivity of N-Isocyanates with Primary and Secondary Amines: Access to Pyridazinones and Triazinones.
abstract: Cascade reactions for the synthesis of 1,2,4-triazinones and 5-aminopyridazinones are reported using α-ketocarbazones as N-isocyanate precursors and exploiting the divergent reactivity observed with primary and secondary amines. Triazinones were formed with primary amines, likely through addition of the amine on the N-isocyanate, followed by cyclization (condensation) on the ketone. In contrast, such cyclization is impossible for secondary amines; this allows in situ formation of enamines, which, upon cyclization, generate 5-amino pyridazinones. This sequence further illustrates the versatility of N-isocyanates in heterocyclic synthesis and provides a rare example of carbon nucleophiles reacting with N-isocyanates.
authors: Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa , 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
authors: Joshua S
authors: JS
authors: Derasp
authors: Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa , 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
authors: Jean-François
authors: JF
authors: Vincent-Rocan
authors: Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa , 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada.
authors: André M
authors: AM
authors: Beauchemin
mesh_terms: D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D017953:Isocyanates / Q000737:chemistry*; D015394:Molecular Structure; D011724:Pyridazines / Q000138:chemical synthesis* / Q000737:chemistry; D014227:Triazines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000588:Amines; D017953:Isocyanates; D011724:Pyridazines; D014227:Triazines