C=CC=C.C=C          C1C=CCCC1           Diels-Alder
C=CC=C              C1C=CC1             Electrocyclic_4e
C(=O)O[H].CO[H]     C(=O)OC.O([H])[H]   Esterification      1,2,3,5,6,4,7
C=C.BrBr            C(CBr)Br            Bromination
