On the use of multi-parameter free energy relationships: the rearrangement of (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into (2-aryl-5-phenyl-2H-1,2,3-tryazol-4-yl)ureas
- Autori: D'Anna, F; Frenna, V; Lanza, CZ; Macaluso, G; Marullo, S; Spinelli, D; Spisani, R; Petrillo, G
- Anno di pubblicazione: 2010
- Tipologia: Articolo in rivista (Articolo in rivista)
- Parole Chiave: ring to ring interconversion, structure/reactivity relationships, changeover of mechanism
- OA Link: http://hdl.handle.net/10447/50367
Abstract
By usingamulti-parameterapproach(acombinationofHammett/Ingold-Yukawa-Tsuno/Fujita-Nishioka free energyrelationships)themononuclearrearrangementsofheterocycles(MRH)ratesfor five new ortho-substitutedandtennewdi-,tri-,ortetra-substituted(Z)-arylhydrazonesof5-amino-3-benzoyl- 1,2,4-oxadiazoleintotherelevant(2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas(indioxane/waterandin a largerangeofpSþ values)havebeenrelatedtotheelectronicandproximityeffectsexertedbythe present substituents,alsoconsideringpreviousresultsonsomemono meta- and para-substituted(Z)- arylhydrazones.Ineverycase,excellentcorrelationcoefficients havebeencalculated(r2 or R2 0.996). Once morethestudyofMRHhasfurnishedaninterestingpanelofdifferentreactivity(threepathwaysof reaction havebeenevidenced:general-base-catalyzed,uncatalyzed,andspecific-acid-catalyzed)andthis has beenusefulinenlighteninghowpolysubstitutioncandifferentlyaffecttheMRHrates.Moreover2,6- disubstitutiononthe(Z)-arylhydrazonomoietycausesasignificantincreaseofthereactivityinallofthe three studiedpathways.Allofthecollecteddataappearusefulforunderstandingstructure-reactivity/ activity relationshipsinpolysubstitutedcompounds.