Oxepin valence tautomer 1 is more stable than oxide valence tautomer 2 in 1, Zdisubstituted arene 1, Zoxides. l With few exceptions sufficient 2 is present in solution to observe acid- catalyzed isomerization via the NIH shift pathway, which involves migration of R, of cation 3 to either adjacent carbon atom with ultimate formation of 4 and/or 5 (Scheme I). Although the factors that determine the direction of substituent migration are not fully understood, the ...
![1,6-diphenyl-trans-3,4-dibromo-7-oxabicyclo[4.1.0]heptane结构式](https://image.chemsrc.com/caspic/050/102342-19-8.png)
