Although the parent 2-pyrone is known to react with simple o-benzynes to produce naphthalene derivatives, there appear to be no examples of the successful reaction of coumarin, a benzo-annulated 2-pyrone analogue, with an aryne. We report such a process here using benzynes generated by the hexadehydro-Diels-Alder reaction to produce phenanthrene derivatives (i.e., benzo-annulated naphthalenes). Density functional theory computations were used to help understand the difference in reactivity between 2-pyrone and the slower trapping agent, coumarin. Finally, the reaction of o-benzyne itself [from o-(trimethylsilyl)phenyl triflate and CsF] with coumarin was shown to be viable, although slow.
|Original language||English (US)|
|Number of pages||5|
|State||Published - Mar 19 2021|
Bibliographical noteFunding Information:
The contributions of Professor R. W. Hoffmann (University of Marburg, Marburg, Germany) through both his Ph.D. thesis research in the laboratory of G. Wittig (e.g., ref ) and his 1967 classic monograph on “dehydrobenzene” (ref ) are acknowledged for providing a foundation that has guided an immense amount of ensuing advances in aryne chemistry. Support for this research was provided by the National Institutes of General Medical Sciences (R35 GM127097) and the National Science Foundation (CHE 1665389). Some of the NMR spectral data were recorded using instrumentation funded through the National Institutes of Health Shared Instrumentation Grant program (S10OD011952). Some of the mass spectrometry data were collected at the Analytical Biochemistry Shared Resource in the Masonic Cancer Center at the University of Minnesota with instrumentation funded in part by a Cancer Center Support Grant (CA-77598). X-ray data were collected on a diffractometer purchased with funds from a grant from the National Science Foundation (MRI 1229400).