What is "vinyldithiin"

Vinyldithiins, more precisely named 3-vinyl-4H-1,2-dithiin and 2-vinyl-4H-1,3-dithiin, are organosulfur phytochemicals formed in the breakdown of allicin from crushed garlic (Allium sativum). Vinyldithiins are Diels-Alder dimers of thioacrolein, HC=CHCH=S, formed in turn by decomposition of allicin. In garlic supplements, vinyldithiins are only found in garlic oil macerates that are made by incubation of crushed garlic in oil.