Abstract:
The concept of an aromatic seven membered ring containing a carboxyl group was introduced in 1945 by Dewar (Dewar M. J. S., Nature, 1945, 155, 50) to interpret the chemical behaviour of stipitatic acid. Such a system is called tropone and the corresponding hydroxy derivatives, tropolones. One naturally occurring derivative is β-isopropyl-γ-(3-methylbut-2-enyl)-tropolone, nootkatin I (Duff S. R., Erdman H., and Harvey W. E., Acta. Chem. Scand., 1954, 8, 1073). This structure has been established by physical methods and chemically by degradation but nootkatin has not yet been synthesised.
