Lewis acid-induced intramolecular Friedel-Crafts cyclization of 1,3-bis-exocyclic dienes. a new route to 4a-methyltetrahydrofluorenes.

ABSTRACT

[reaction see text] An efficient new method for constructing the 4a-methyltetrahydrofluorene skeleton was achieved via Friedel-Crafts intramolecular cyclization of 1,3-bis-exocyclic dienes. This strategy offers a simple and promising method for accessing complex structures.