How cysteine reacts with citral: an unexpected reaction of beta,beta-disubstituted acroleins with cysteine leading to hexahydro-1,4-thiazepines.
The reaction of beta,beta-disubstituted acroleins [3-methyl-2-butenal (1), 3-methyl-2-hexenal (2), and citral (3)] with cysteine gave 1:2 adducts of a novel structural type, namely hexahydro-1,4-thiazepines. To the best of our knowledge, the spontaneous formation of a seven-membered heterocycle from the addition of cysteine to alpha,beta-unsaturated aldehydes is unprecedented. The adduct 6 obtained from citral, under acidic conditions, reacted further to give the new bicyclic compound 8.
Starkenmann
Christian
C
R&D Division, FIRMENICH SA, P.O. Box 239, CH-1211 Geneva 8, Switzerland. christian.starkenmann@firmenich.com
Brauchli
Robert
R
Maurer
Bruno
B
D000171:Acrolein / Q000737:chemistry*; D000080462:Acyclic Monoterpenes; D000447:Aldehydes / Q000737:chemistry; D003543:Cysteamine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D039821:Monoterpenes / Q000737:chemistry*; D013841:Thiazepines / Q000737:chemistry*
D000080462:Acyclic Monoterpenes; D000447:Aldehydes; D039821:Monoterpenes; D013841:Thiazepines; D003543:Cysteamine; D000171:Acrolein; C007076:citral