Synthesis of a series of novel fused pyrazolines and pyrazoles has been accomplished in good yields by regioand diastereoselective 1,3-dipolar cycloaddition of enamines of indan-1-one 1a-c towards C-aryl-N-phenylnitrilimines 2d-f. The structure of the cycloadducts was elucidated by 1D and 2D NMR studies.
Reactions. -The synthesis of title compounds (III) is accomplished by cycloaddition of dihydroisoquinolinium salts (I) and chromanones (II). Independent of the electronic effects of the substituents in the aryl residue of (II) the reaction is regio-and stereoselective. The acid-catalyzed isomerization of strained spiro compounds (III) affords the more stable pyrrole derivative (IV). -(ASKRI, M.; RAMMAH*, M.; MONNIER-JOBE, K.; CIAMALA, K.; KNORR, M.; STROHMANN, C.; Lett.
A new and convenient procedure for the preparation of 3,6-diaryl-2(1 H)-pyridones via 1,3-dipolar cycloaddition of münchnonimines to acrylic esters is described.
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