Tetrahedron letters

A novel synthesis of 1, 3, 5-trisubstituted pyrazoles through a spiro-pyrazoline intermediate via a tandem 1, 3-dipolar cycloaddition/elimination

S Dadiboyena, EJ Valente, AT Hamme

Index: Dadiboyena, Sureshbabu; Valente, Edward J.; Hamme II, Ashton T. Tetrahedron Letters, 2009 , vol. 50, # 3 p. 291 - 294

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Citation Number: 30

Abstract

The syntheses of an important class of hitherto unreported 1, 3, 5-pyrazoles, inspired by an unanticipated eliminatory ring opening are described. The reported pyrazole compounds were constructed through the Huisgen cyclization of 2-methylene-1, 3, 3-trimethylindoline and an in situ generated nitrile imine. The newly formed spiro-pyrazoline intermediate presumably then undergoes a ring opening/elimination process to afford a pyrazole, as ...