cinnamaldehyde

    H      H
     \    /
      C--C    H       O
     /    \   |      //
 H--C      C--C==C--C
     \    /      |   \
      C--C       H    H
     /    \ 
    H      H

Cinnamaldehyde, 3-phenylpropenal, is an aldehyde and the compound that gives cinnamon its flavor, odor, and general cinnamon-ness.