The crowded ketenes, (2,4,6-R3C6H2)2C=C=O, R = Pri, Me, undergo intramolecular cyclization of the ketene oxygen on an o-alkyl group to give substituted isochromenes. The reaction is two orders of magnitude faster at 170°C for R = Pri than for R = Me. A stepwise reaction involving a 1,5-sigmatropic rearrangement to a conjugated tetraenal which does not accumulate and rapidly cyclizes to the isochromene is suggested.
|Number of pages||2|
|Journal||Journal of the Chemical Society. Perkin Transactions 2|
|State||Published - 1 Jan 1997|
ASJC Scopus subject areas
- Chemistry (all)