Beyond Schmittel and Myers-Saito cyclizations: rearrangements of 4-heteroatom-1,2-hexa-diene-5-ynes.
The thermal rearrangements of 4-heteroatom-1,2-hexadiene-5-ynes (2) were studied at the BLYP/6-311+G//BLYP/6-31G level of theory. Cyclization of 2 to heteroatom-containing cyclopentadienyl structures (6) competes with the Claisen-type rearrangement to acyclic, allenic structures. Cyclizations to cyclobutene (4)- and cyclohexadiene (8)-derived heterocycles are not feasible as a result of high reaction barriers and lower-lying alternative pathways. [structure: see text]
Bui
Binh H
BH
Department of Chemistry, University of Georgia, Athens, GA 30605-2556, USA.
Schreiner
Peter R
PR