Structural effects on sigmatropic shifts in heteroaromatic allyl ethersElectron...

• Author(s): Araújo, Nuna C. ; Barroca, Pedro M. M. ; Bickley, Jamie F. ; Brigas, Amadeu F. ; Cristiano, Maria Lurdes Santos ; Johnstone, Robert A. W. ; Loureiro, Rui M. S. ; Pena, Paula C. A.
• Date: 2002
• Persistent ID: http://hdl.handle.net/10400.1/4250
• Origin: Sapientia - Universidade do Algarve
• Document Type: Article
• Language: English

Description

In contrast to the known thermal, exclusively [3,3], O- to N- rearrangement of allyl groups in phenyltetrazoles (1, Scheme 1), the comparable migration of the allyl group in pseudosaccharyl ethers (3; Scheme 2) has been shown to proceed through both [1,3]- and [3,3]-mechanisms, 4, 5; for the pseudosaccharyl derivative of the natural product myrtenol (6; Scheme 3) only the product 7 of a [1,3]-shift has been observed; crystallographic data and theoretical calculations provide an explanation of this ease of [1,3]-isomerization and the observed selectivity as being due to conformational constraints and electronic factors.