"Cinnamaldehyde is the organic compound that gives cinnamon its flavor and odor.[1] This pale yellow viscous 
liquid occurs naturally in the bark of cinnamon trees and other species of the genus Cinnamomum. The essential oil of cinnamon bark is about 90% cinnamaldehyde."
"Cinnamaldehyde was isolated from cinnamon essential oil in 1834 by Dumas and Péligot and synthesized in the laboratory by Chiozza in 1854."
"The natural product is trans-cinnamaldehyde. The molecule consists of a phenyl group attached to an unsaturated aldehyde. As such, the molecule can be viewed as a derivative of acrolein. Its color is due to the π → π* transition: increased conjugation in comparison with acrolein shifts this band towards the visible."