1,4-benzenediyl diradical formation

Benzenediyl diradical formation from enediyne via electrocyclization. 

Formation of a substituted benzene through 1,4-benzenediyl diradical formation from enediyne via electrocychzation. 

T,K-diradical intermediate 35 (and hence the transition state leading to it) over the 1,4-benzenediyl diradical species 2 involved in the Bergman cyclization ensured that the reaction proceeded under much milder conditions (typically 37-100 °C) than are usually required for Bergman cyclizations. Mild thermolysis of 34 in 1,4-cyclohexadiene afforded 36 in 60% yield. It is interesting that methyl substitution at the allene terminus of 34 caused acceleration of the cyclization (approximately six times faster than 34) and this was presumably due to formation of a more stable diradical intermediate. ... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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