Diels-Alder approach to biaryls: elucidation of competing tandem [2+2] cycloaddition/[1,3] sigmatropic shift pathway.
Reaction of 2-halo-6-nitrophenylacetylene with an electron deficient diene gives rise to a [4+2] cycloaddition/cycloreversion biaryl product and a bicyclo[4.2.0]octadiene resulting from a competing [2+2] cycloaddition pathway. The cyclobutene can be opened to give a mixture of cyclooctatriene and biaryl in varying amounts depending on heat and light exposure. The conversion of the cyclobutene into biaryl occurs through a [1,3] sigmatropic carbon shift followed by [4+2] cycloextrusion of ethylene gas.
Ashburn
Bradley O
BO
Department of Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, Oregon 97331, USA.
Carter
Rich G
RG
Zakharov
Lev N
LN
D001713:Biphenyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D003503:Cyclobutanes / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D001713:Biphenyl Compounds; D003503:Cyclobutanes