Regioselective Synthesis of 3-Carbo-5-phosphonylpyrazoles through a One-Pot Claisen-Schmidt/1,3-Dipolar Cycloaddition/Oxidation Sequence

Anthony R. Martin (1) , Kishor Mohanan (1) , Loic Toupet (2) , Jean-Jacques Vasseur (1) , Michael Smietana (1)

1 IBMM - Institut des Biomolécules Max Mousseron [Pôle Chimie Balard]
2 IPR - Institut de Physique de Rennes

A one-pot reaction involving an aldehyde, a methyl ketone, and the Bestmann-Ohira reagent has been developed for the synthesis of variously substituted 3-carbo-5-phosphonylpyrazoles. Our synthetic methodology features a domino Claisen- Schmidt/1,3-dipolar cycloaddition/oxidation sequence,which leads to the target compounds in excellent yields. We further demonstrated that this unprecedented sequence could also be combined with a copper-catalyzed azide- alkyne cycloaddition in a one-pot, four-step cascade process generating five new bonds and two heterocyclic rings.

Mots clés: Click chemistry; Cycloaddition; Heterocycles; Multicomponent reactions; Synthetic methods; Organophosphorus compounds

Domaines: Chimie organique

Anthony R. Martin, Kishor Mohanan, Loic Toupet, Jean-Jacques Vasseur, Michael Smietana. Regioselective Synthesis of 3-Carbo-5-phosphonylpyrazoles through a One-Pot Claisen-Schmidt/1,3-Dipolar Cycloaddition/Oxidation Sequence. European Journal of Organic Chemistry, 2011, 2011 (17), pp.3184-3190. ⟨10.1002/ejoc.2011100167⟩. ⟨hal-00616408⟩