cis-3-Hexenal, also known as (Z)-3-hexenal and leaf aldehyde, is colorless liquid and an aroma compound with an intense grassy-green odor of freshly cut green grass and leaves. It is one of the major volatile compounds in ripe tomatos.It is produced in small amounts by most plants and it acts as an attractant to many predatory insects. It is also a pheromone in many insect species.
cis-3-Hexenal is an aldehyde. It is relatively unstable and isomerizes into the conjugated trans-2-hexenal. The related alcohol cis-3-hexen-1-ol is much more stable. It has a similar but weaker smell and is widely used in flavors and perfumes.