6-APDB, also known as 6-(2-aminopropyl)-2,3-dihydrobenzofuran or as 4-desoxy-MDA, is an entactogen of the phenethylamine, amphetamine, and dihydrobenzofuran families. It is an analogue of MDA where the heterocyclic 4-position oxygen from the 3,4-methylenedioxy ring has been replaced with a methylene bridge. 5-APDB (3-desoxy-MDA) is an analogue of 6-APDB where the 3-position oxygen has been replaced with a methylene instead. 5-APDB was developed by a team led by David E. Nichols at Purdue University as part of their research into non-neurotoxic analogues of MDMA and first described in 1993.