The hydrochloride hydrates of pentylone and dibutylone and the hydrochloride salt of ephylone: the structures of three novel designer cathinones

Abstract

The structures of the hydrochloride hydrates of pentylone and dibutylone and the hydrochloride salt of ephylone, three new clandestinely-manufactured designer cathinones are described. Pentylone is (±)-1-(1,3-benzodioxol-5-yl)-2-(methylamino)pentan-1-one, dibutylone is (±)-1-(1,3-benzodioxol-5-yl)-2-(dimethylamino)butan-1-one, and ephylone is (±)-1-(1,3-benzodioxol-5-yl)-2-(ethylamino)pentan-1-one. These three drugs have recently appeared in law enforcement seizures of illicit drug materials and are referred to as NPS (new psychoactive substances). The free base pentylone crystallizes as the hydrochloride monohydrate salt with H bonds extending from the protonated amine to the Cl⁻ anion very close to a center of symmetry, thence to a water of hydration, resulting in an interesting six-sided species of approximately chair conformation whose components are linked by hydrogen bonds. An interesting feature of the dibutylone free base is that it crystallizes as the HCl sesquihydrate salt. Most of the street drugs crystallize as their hydrates; but, unlike most of them, dibutylone HCl^. 1.5H₂O crystallizes as a kryptoracemate in space group P2₁2₁2₁. A kryptoracemic crystal is one whose asymmetric unit contains a racemic pair, but still belongs in a Sohncke space group. The phenomenon was recognized relatively recently and, to date, there are very few drugs identified as crystallizing thus (for more on this topic, see below). In this structure, both independent amine cations have a chloride counter-anion, and they share three water molecules of crystallization, with the chloride anions and the waters forming an interesting H-bonded cyclic array. The free base ephylone crystallizes as the HCl salt and is a brand new substance, not appearing until about November 2015. The packing of all three of these cathinones contains “sandwich” π-π stacking interactions where the phenyl rings of the cations are stacked face-to-face with each other, with distances ranging from 3.531 to 3.862 Å. These compounds are among the most recent examples of cathinone-based stimulants designed to circumvent existing drug laws, and they represent a new danger to recreational drug users.