title: Sigmatropic rearrangements in 5-allyloxytetrazoles.
abstract: Mechanisms of thermal isomerization of allyl tetrazolyl ethers derived from the carbocyclic allylic alcohols cyclohex-2-enol and 3-methylcyclohex-2-enol and from the natural terpene alcohol nerol were investigated. In the process of the syntheses of the three 1-aryl-5-allyloxytetrazoles, their rapid isomerization to the corresponding 1-aryl-4-allyltetrazol-5-ones occurred. The experiments showed that the imidates rearrange exclusively through a [3,3']-sigmatropic migration of the allylic system from O to N, with inversion. Mechanistic proposals are based on product analysis and extensive quantum chemical calculations at the DFT(B3LYP) and MP2 levels, on O-allyl and N-allyl isomers and on putative transition state structures for [1,3']- and [3,3']-sigmatropic migrations. The experimental observations could be only explained on the basis of the MP2/6-31G(d,p) calculations that favoured the [3,3']-sigmatropic migrations, yielding lower energies both for the transition states and for the final isomerization products.
authors.affiliation: Department of Chemistry and Pharmacy, F.C.T. and CCMAR, University of Algarve, Campus de Gambelas, 8005-039 Faro, Portugal.
authors.forename: Luís M T
authors.initials: LM
authors.lastname: Frija
authors.forename: Igor
authors.initials: I
authors.lastname: Reva
authors.forename: Amin
authors.initials: A
authors.lastname: Ismael
authors.forename: Daniela V
authors.initials: DV
authors.lastname: Coelho
authors.forename: Rui
authors.initials: R
authors.lastname: Fausto
authors.forename: M Lurdes S
authors.initials: ML
authors.lastname: Cristiano
mesh_terms: D000080462:Acyclic Monoterpenes; D000438:Alcohols / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry; D004987:Ethers / Q000737:chemistry; D007536:Isomerism; D013729:Terpenes / Q000737:chemistry; D013777:Tetrazoles / Q000737:chemistry*
chemical_list: D000080462:Acyclic Monoterpenes; D000438:Alcohols; D000498:Allyl Compounds; D004987:Ethers; D013729:Terpenes; D013777:Tetrazoles; C007836:geraniol