Studies on Sequential Claisen Rearrangement: Charge-Accelerated [3,3]-Sigmatropic Rearrangement Leading to Polyheterocycles.

A number of quinolone-annulated pentacycles have been regioselectively synthesized in 90-95% yields by sequential Claisen rearrangements. The second synthesis is anhydrous AlCl3-catalyzed charge-accelerated aromatic Claisen rearrangement of 1-aryloxymethyl-6-alkyl-3H-pyrano[2,3-c]quinolin-5(6H)-ones in dichloromethane at rt for 5-10 min. The precursors were synthesized by the thermal [3,3]-sigmatropic rearrangement of the corresponding ethers. [ABSTRACT FROM AUTHOR]