Thiols. That's the compound. It's a sulfur analogue supposedly found in the original rks, and they're not terpenes, and aren't tested for on current common Terpenoid analysis.
3-Methyl-2-butene-1-thiol is found in alcoholic beverages. Substance responsible for ``sun-struck'' flavour of beer. 3-Methyl-2-butene-1-thiol is found in coffee. 3-Methyl-2-butene-1-thiol is used in food flavourings 3-Methyl-2-butene-1-thiol belongs to the family of Hemiterpenes. These are terpenes containing only one isoprene unit (C5-terpene).