Sigmatropic rearrangements in 5-allyloxytetrazoles. | - CCMAR -

Journal Article

TitleSigmatropic rearrangements in 5-allyloxytetrazoles.
Publication TypeJournal Article
AuthorsFrija, LMT, Reva, I, Ismael, A, Coelho, DV, Fausto, R, Cristiano, MLS
Year of Publication2011
JournalOrg Biomol Chem
Date Published2011 Sep 7
KeywordsAlcohols, Allyl Compounds, Ethers, Isomerism, Terpenes, Tetrazoles

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.


Alternate JournalOrg. Biomol. Chem.
PubMed ID21750817