Experimental and Theoretical DFT Investigations in the [2,3]-Wittig-Type Rearrangement of Propargyl/Allyl-Oxy-Pyrazolones

Lucia De Crescentini; Gianfranco Favi; Giacomo Mari; Gianluca Ciancaleoni; Marcello Costamagna; Stefania Santeusanio; Fabio Mantellini

doi:10.3390/molecules26216557

Experimental and Theoretical DFT Investigations in the [2,3]-Wittig-Type Rearrangement of Propargyl/Allyl-Oxy-Pyrazolones

Molecules. 2021 Oct 29;26(21):6557. doi: 10.3390/molecules26216557.

Authors

Lucia De Crescentini¹, Gianfranco Favi¹, Giacomo Mari¹, Gianluca Ciancaleoni², Marcello Costamagna², Stefania Santeusanio¹, Fabio Mantellini¹

Affiliations

¹ Department of Biomolecular Sciences, Section of Organic Chemistry and Organic Natural Compounds, University of Urbino "Carlo Bo", Via I Maggetti 24, 61029 Urbino, PU, Italy.
² Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, PI, Italy.

Abstract

Here we report the synthesis of interesting 3-alkyl-4-hydroxy-1-aryl-4-(propa-1,2-dienyl)1H-pyrazol-5(4H)-ones and 9-alkyl-7-aryl-1-oxa-7,8-diazaspiro[4.4]nona-3,8-dien-6-ones, starting from 1,2-diaza-1,3-dienes (DDs) and propargyl alcohol. The reaction proceeds through a sequence Michael-type nucleophilic attack/cyclization/[2,3]-Wittig rearrangement. In the same way, the reaction between the aforementioned DDs and allyl alcohol furnished 4-allyl-4-hydroxy-3-alkyl-1-aryl-1H-pyrazol-5(4H)-ones. A DFT study was also carried out, in order to have decisive clarifications about the mechanism.

Keywords: 1,2-diaza-,1,3-dienes; DFT study; [2,3]-Wittig rearrangement; allyl alcohol; propargyl alcohol; pyrazolones.