Indanones and indenols from 2-alkylcinnamaldehydes via the intramolecular Friedel-Crafts reaction of geminal diacetates.
When treated with Ac2O at rt in the presence of 4-6 mol % FeCl3, 2-alkylcinnamaldehydes are converted to 2-alkyl-1H-inden-1-yl acetates through the intermediacy of gem-diacetates. Methanolysis of the indenyl acetates yields the corresponding indenols. Saponification yields 2-alkylindanones, providing, in effect, an intramolecular acylation employing catalytic levels of acid.
Womack
Gary B
GB
Corporate R&D Division, Firmenich, Inc., P.O. Box 5880, Princeton, New Jersey 08543, USA. gary.womack@firmenich.com
Angeles
John G
JG
Fanelli
Vincent E
VE
Indradas
Brinda
B
Snowden
Roger L
RL
Sonnay
Philippe
P
D000085:Acetates / Q000737:chemistry*; D000171:Acrolein / Q000031:analogs & derivatives* / Q000737:chemistry; D003500:Cyclization; D007189:Indans / Q000138:chemical synthesis* / Q000737:chemistry; D007192:Indenes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D000085:Acetates; D007189:Indans; D007192:Indenes; D000171:Acrolein; C012843:cinnamaldehyde