4-Thiosymbescaline (4-TSB), also known as 3,5-diethoxy-4-methylthiophenethylamine, is a chemical compound of the phenethylamine and scaline families related to mescaline. It is the analogue of symbescaline in which the methoxy group at the 4 position has been replaced with a methylthio group. The compound is one of two possible thiosymbescaline (TSB) positional isomers, the other being 3-thiosymbescaline (3-TSB).
In his book PiHKAL (Phenethylamines I Have Known and Loved) and other publications, Alexander Shulgin lists 4-TSB's dose as greater than 240mg orally and its duration as unknown. The effects of 4-TSB have been reported to include a "real effect" and a little spaciness at 80mg orally, twinges at 160mg orally, and "no effects at all" at 240mg orally. It was concluded that the compound is probably inactive.
The chemical synthesis of 4-TSB has been described.
4-TSB was first described in the scientific literature by Shulgin and Peyton Jacob III in 1984. Subsequently, it was described in greater detail by Shulgin in PiHKAL in 1991.