Psilacetin derivatives: fumarate salts of the methyl–ethyl, methyl–allyl and diallyl variants of the psilocin prodrug

The solid-state structures of the salts of three psilacetin derivatives, namely, 4-acetoxy- N -ethyl- N -methyltryptammonium (4-AcO-MET) hydrofumarate {systematic name: [2-(4-acetyloxy-1 H -indol-3-yl)ethyl](methyl)ethylazanium 3-carboxyprop-2-enoate}, C 15 H 21 N 2 O 2 + ·C 4 H 3 O 4 − , 4-acetoxy- N -allyl- N -methyltryptammonium (4-AcO-MALT) hydrofumarate {systematic name: [2-(4-acetyloxy-1 H -indol-3-yl)ethyl](methyl)prop-2-enylazanium 3-carboxyprop-2-enoate}, C 16 H 21 N 2 O 2 + ·C 4 H 3 O 4 − , and 4-acetoxy- N , N -diallyltryptammonium (4-AcO-DALT) fumarate–fumaric acid (1/1) (systematic name: bis{[2-(4-acetyloxy-1 H -indol-3-yl)ethyl]diprop-2-enylazanium} but-2-enedioate–( E )-butenedioic acid (1/1)), 2C 18 H 23 N 2 O 2 + ·C 4 H 2 O 4 2− ·C 4 H 4 O 4 , are reported. All three salts possess a protonated tryptammonium cation. The 4-AcO-MET and 4-AcO-MALT compounds are charge-balanced by 3-carboxyacrylate (hydrofumarate) anions. The 4-AcO-DALT complex crystallizes as a two-to-one tryptammonium-to-fumarate salt, which co-crystallizes with a fumaric acid molecule. Each structure is consolidated by N—H...O and O—H...O hydrogen bonds.