title: Conversion of 2-alkylcinnamaldehydes to 2-alkylindanones via a catalytic intramolecular Friedel-Crafts reaction.
abstract: The preparation of indanones by the intramolecular acylation of 3-arylpropanoic acids or halides requires the use of noncatalytic acid promoters. In the presence of 5-10 mol % FeCl(3), in situ generated dimethyl acetals of (E)-2-alkylcinnamaldehydes cyclize to 1-methoxy-2-alkyl-1H-indenes in good-to-high yields. The 1-methoxyindenes were converted in high yield into 2-alkylindanones by treatment with triethylamine, to effect isomerization to the isomeric enol ethers, followed by acid-catalyzed hydrolysis. Thus, a catalytic, intramolecular Friedel-Crafts reaction leading to 2-alkylindanones from 2-alkylcinnamaldehydes was developed.
authors: Firmenich, Corporate R&D Division, P.O. Box 5880, Princeton, New Jersey 08543, USA. gary.womack@firmenich.com
authors: Gary B
authors: GB
authors: Womack
authors: John G
authors: JG
authors: Angeles
authors: Vincent E
authors: VE
authors: Fanelli
authors: Christie A
authors: CA
authors: Heyer