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Synthesis of spiro‐1‐pyrazolines by the 1,3‐dipolar cycloaddition of exocyclic α,β‐unsaturated ketones with diazomethane

1999; Wiley; Volume: 36; Issue: 5 Linguagem: Inglês

10.1002/jhet.5570360517

1943-5193

Artur M. S. Silva, José A. S. Cavaleiro, Albert Lévai, Tamás Patonay,

Synthesis and Reactivity of Heterocycles

Abstract 1,3‐Dipolar cycloadditions of exocyclic α,β‐unsaturated ketones 1‐22 with diazomethane afforded spiro‐1‐pyrazolines 23‐44 in a diastereospecific reaction. The structure and stereochemistry of each compound synthesised has been elucidated by nmr spectroscopic measurements and other analytical techniques. It has been proven that the stereochemistry of the starting α,β‐enones was retained in the course of these cycloadditions.