organic compounds
The hydrochloride salt of 4-hydroxy-N,N-di-n-propyltryptamine (4-HO-DPT)
aUniversity of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA, and bCaaMTech, LLC, 58 East Sunset Way, Suite 209, Issaquah, WA 98027, USA
*Correspondence e-mail: dmanke@umassd.edu
The title compound, 4-hydroxy-N,N-di-n-propyltryptammonium (4-HO-DPT) chloride {systematic name: N-[2-(4-hydroxy-1H-indol-3-yl)ethyl]-N-propylpropan-1-aminium chloride}, C16H25N2O+·Cl−, has a singly protonated tryptammonium cation and one chloride anion in the A series of N—H⋯Cl and O—H⋯Cl hydrogen bonds connect the ions together in ladder chains along [010].
Keywords: crystal structure; tryptamines; indoles; hydrogen bonding.
CCDC reference: 2045782
Structure description
Psilocybin, N,N-dimethyl-4-phosphoryloxytryptamine, is a naturally occurring tryptamine found in `magic mushrooms'. When consumed orally, the phosphate group of psilocybin is hydrolyzed to generate psilocin, 4-hydroxy-N,N-dimethyltryptamine. Psilocybin functions as a prodrug of psilocin, its active metabolite, which binds to and stimulates the human serotonin 2a receptor (Geiger et al., 2018), causing profound changes to human consciousness, which are generally described as a `psychedelic' experience. Recently, human serotonin 2a receptor agonists (e.g. LSD, ayahuasca/DMT, psilocybin/psilocin, peyote/mescaline, 5-MeO-DMT) have shown incredible potential for treating a wide variety of the world's most debilitating, intractable, and costly health problems, including anxiety, depression, addiction, post-traumatic stress disorder (PTSD) and inflammation (Johnson & Griffiths, 2017; Carhart-Harris & Goodwin, 2017). 4-Hydroxy-N,N-di-n-propyltryptamine (4-HO-DPT) is a structural analogue of psilocin and produces similar (though not identical) psychedelic effects in human subjects (Shulgin & Shulgin, 2016). The compound 4-HO-DPT is somewhat more hydrophobic than psilocin on account of substituting the di-n-methylamine group with a di-n-propylamine group. When used as pharmaceuticals, are often converted to their hydrochloride salts to increase their solubility in water, and thus improving drug delivery (Stahl & Wermuth, 2011). Herein we report the solid-state structure of 4-hydroxy-N,N-di-n-propyltryptammonium (4-HO-DPT) chloride (Fig. 1), which is the first of a psilocin analogue as its hydrochloride salt.
The 4-HO-DPT cation and the chloride anion are held together in the via O—H⋯Cl hydrogen bonds. The cation possesses a near planar indole group, with a mean deviation from planarity of 0.011 Å. The ethylamino group is turned away from the plane with a C1—C2—C9—C10 torsion angle of 101.54 (18)°. The N—H of the indole ring, and the N—H of the ammonium group also both hydrogen bond to other symmetry-generated chloride anions through N—H⋯Cl interactions (Table 1). The N—H⋯Cl indole-to-chloride hydrogen bond and the O—H⋯Cl hydrogen bond combine to link the ions together in chains with graph-set notation C21(8). The N—H⋯Cl indole-to-chloride hydrogen bonds and the N—H⋯Cl ammonium-to-chloride hydrogen bonds combine to generate rings with graph-set notation R42(18) (Etter, et al. 1990). The N—H⋯Cl ammonium-to-chloride hydrogen bonds and O—H⋯Cl hydrogen bonds combine to generate rings with graph-set notation R42(20). The two rings and chains combine to give ladder chains along [010], Fig. 2.
The most closely related structure to the title compound is the two-to-one 4-HO-DPT-to-fumarate salt, which crystallizes as a tetrahydrate (WUCGAF; Chadeayne et al., 2019b). There are six other structures of 4-hydroxy-substituted tryptamines that have been reported. These are the active metabolite of psilocybin - psilocin, or 4-hydroxy-N,N-dimethyltryptamine (PSILIN; Petcher & Weber, 1974), the active metabolite of baeocystin-norpsilocin, or 4-hydroxy-N-methyltryptamine, which has been reported as its freebase (CCDC 1992279; Chadeayne et al., 2020b) and its fumarate salt (CCDC 1992278; Chadeayne et al., 2020b), and the active metabolite of aeruginascin − 4-hydroxy-N,N,N-trimethyltryptamine (XUXFAA; Chadeayne, Pham, Reid et al., 2020) which is reported as its iodide salt. The structure of the synthetic psychedelic 4-HO-MiPT has also been reported as its one-to-one hydrofumarate salt (RONSUL; Chadeayne et al., 2019a) and as its two-to-one fumarate salt (CCDC 1987588; Chadeayne et al., 2 2020a).
Synthesis and crystallization
Freebase 4-hydroxy-N,N-di-n-propyltryptamine (50 mg, 0.19 mmol) was dissolved in dichloromethane, and 160 µL of hydorochloric acid (1.25 M in ethanol, 0.20 mmol) were added with stirring at room temperature. The mixture was stirred for 30 minutes, resulting in a white precipitate which was isolated via vacuum filtration and washed with diethyl ether to yield 28 mg of the salt. A second crop was collected by concentrating and cooling the filtrate to give another 13 mg of the salt (73% yield). Crystals suitable for X-ray diffraction studies were grown by the slow evaporation of a methylene chloride/methanol mixture. The sample was analyzed by nuclear magnetic resonance. 1H NMR (400 MHz, D2O): δ 7.07 (s, 1 H, ArH), 7.04–6.96 (m, 2 H, ArH), 6.47 (dd, J = 6.1, 2.4 Hz, 1 H, ArH), 3.42–3.30 (m, 2 H, CH2), 3.20–3.07 (m, 2 H, CH2), 3.00 (dd, J = 10.1, 6.4 Hz, 4 H, CH2), 1.60 (h, J = 6.8 Hz, 4 H, CH2), 0.84 (t, J = 7.4 Hz, 6 H, CH3); 13C NMR (100 MHz, D2O): δ 149.9 (ArC), 138.8 (ArC), 123.3 (ArC), 123.2 (ArC), 115.9 (ArC), 108.5 (ArC), 104.5 (ArC), 103.7 (ArC), 54.7 (AkC), 53.7 (AkC), 21.2 (AkC), 16.8 (AkC), 10.0 (AkC).
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2
|
Structural data
CCDC reference: 2045782
https://doi.org/10.1107/S2414314620015461/sj4218sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620015461/sj4218Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314620015461/sj4218Isup3.cml
Data collection: APEX3 (Bruker, 2018); cell
SAINT (Bruker, 2018); data reduction: SAINT (Bruker, 2018); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: publCIF (Westrip, 2010).C16H25N2O+·Cl− | Z = 2 |
Mr = 296.83 | F(000) = 320 |
Triclinic, P1 | Dx = 1.160 Mg m−3 |
a = 7.860 (3) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 10.439 (4) Å | Cell parameters from 9206 reflections |
c = 11.713 (5) Å | θ = 2.6–25.8° |
α = 76.236 (14)° | µ = 0.22 mm−1 |
β = 73.653 (13)° | T = 273 K |
γ = 68.852 (12)° | Block, colourless |
V = 850.0 (6) Å3 | 0.15 × 0.10 × 0.10 mm |
Bruker D8 Venture CMOS diffractometer | 2756 reflections with I > 2σ(I) |
φ and ω scans | Rint = 0.066 |
Absorption correction: multi-scan (SADABS; Bruker, 2018) | θmax = 26.0°, θmin = 2.6° |
Tmin = 0.720, Tmax = 0.745 | h = −9→9 |
27008 measured reflections | k = −12→12 |
3243 independent reflections | l = −14→14 |
Refinement on F2 | 3 restraints |
Least-squares matrix: full | Hydrogen site location: mixed |
R[F2 > 2σ(F2)] = 0.036 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.103 | w = 1/[σ2(Fo2) + (0.0541P)2 + 0.1743P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
3243 reflections | Δρmax = 0.43 e Å−3 |
192 parameters | Δρmin = −0.40 e Å−3 |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
Cl1 | 0.84351 (5) | 0.74832 (4) | 0.23642 (4) | 0.04716 (14) | |
N1 | 0.7748 (2) | 0.03222 (14) | 0.34007 (16) | 0.0578 (4) | |
H1 | 0.790 (3) | −0.0454 (14) | 0.3157 (19) | 0.069* | |
N2 | 0.75749 (17) | 0.34070 (13) | 0.71443 (11) | 0.0422 (3) | |
H2 | 0.8748 (18) | 0.314 (2) | 0.7409 (18) | 0.063* | |
O1 | 0.77173 (17) | 0.46842 (11) | 0.35885 (10) | 0.0506 (3) | |
H1A | 0.797 (3) | 0.5412 (16) | 0.3168 (19) | 0.076* | |
C1 | 0.7077 (2) | 0.05956 (16) | 0.45593 (18) | 0.0531 (4) | |
H1B | 0.668481 | −0.001309 | 0.521524 | 0.064* | |
C2 | 0.7068 (2) | 0.18915 (15) | 0.46130 (15) | 0.0416 (3) | |
C3 | 0.77946 (19) | 0.24542 (15) | 0.34010 (14) | 0.0385 (3) | |
C4 | 0.8114 (2) | 0.37253 (16) | 0.28523 (14) | 0.0413 (3) | |
C5 | 0.8792 (2) | 0.3950 (2) | 0.16234 (16) | 0.0547 (4) | |
H5 | 0.898048 | 0.479641 | 0.125550 | 0.066* | |
C6 | 0.9198 (3) | 0.2913 (2) | 0.09275 (18) | 0.0657 (5) | |
H6 | 0.966338 | 0.308406 | 0.010282 | 0.079* | |
C7 | 0.8929 (3) | 0.1653 (2) | 0.14258 (18) | 0.0636 (5) | |
H7 | 0.921712 | 0.096793 | 0.095694 | 0.076* | |
C8 | 0.8204 (2) | 0.14383 (16) | 0.26682 (17) | 0.0480 (4) | |
C9 | 0.6397 (2) | 0.25770 (17) | 0.57189 (14) | 0.0437 (4) | |
H9A | 0.559043 | 0.212172 | 0.633105 | 0.052* | |
H9B | 0.567594 | 0.354321 | 0.552523 | 0.052* | |
C10 | 0.8050 (2) | 0.24920 (16) | 0.62024 (14) | 0.0437 (4) | |
H10A | 0.860211 | 0.153568 | 0.654519 | 0.052* | |
H10B | 0.898501 | 0.274491 | 0.553374 | 0.052* | |
C11 | 0.7172 (3) | 0.49232 (17) | 0.65963 (16) | 0.0518 (4) | |
H11A | 0.814555 | 0.501143 | 0.588662 | 0.062* | |
H11B | 0.599814 | 0.523916 | 0.633915 | 0.062* | |
C12 | 0.7061 (3) | 0.58502 (19) | 0.74365 (18) | 0.0605 (5) | |
H12A | 0.808731 | 0.542065 | 0.784928 | 0.073* | |
H12B | 0.590170 | 0.596278 | 0.803782 | 0.073* | |
C13 | 0.7149 (3) | 0.72656 (19) | 0.6756 (2) | 0.0640 (5) | |
H13A | 0.829874 | 0.715522 | 0.616365 | 0.096* | |
H13B | 0.708833 | 0.783488 | 0.730965 | 0.096* | |
H13C | 0.611458 | 0.770155 | 0.636457 | 0.096* | |
C14 | 0.6079 (2) | 0.31594 (18) | 0.82147 (15) | 0.0520 (4) | |
H14A | 0.494348 | 0.334255 | 0.794356 | 0.062* | |
H14B | 0.581895 | 0.381292 | 0.875563 | 0.062* | |
C15 | 0.6587 (3) | 0.1708 (2) | 0.88982 (18) | 0.0638 (5) | |
H15A | 0.783677 | 0.144610 | 0.903678 | 0.077* | |
H15B | 0.657852 | 0.106282 | 0.842690 | 0.077* | |
C16 | 0.5201 (4) | 0.1627 (3) | 1.0100 (2) | 0.0906 (8) | |
H16A | 0.521750 | 0.226249 | 1.056699 | 0.136* | |
H16B | 0.554431 | 0.069863 | 1.053005 | 0.136* | |
H16C | 0.396891 | 0.186970 | 0.996033 | 0.136* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1 | 0.0460 (2) | 0.0406 (2) | 0.0602 (3) | −0.01650 (16) | −0.00926 (17) | −0.01564 (16) |
N1 | 0.0652 (9) | 0.0341 (7) | 0.0837 (11) | −0.0083 (6) | −0.0303 (8) | −0.0213 (7) |
N2 | 0.0399 (7) | 0.0438 (7) | 0.0419 (7) | −0.0115 (5) | −0.0077 (5) | −0.0087 (5) |
O1 | 0.0656 (7) | 0.0389 (6) | 0.0501 (7) | −0.0234 (5) | −0.0027 (5) | −0.0128 (5) |
C1 | 0.0553 (9) | 0.0371 (8) | 0.0727 (12) | −0.0163 (7) | −0.0253 (9) | −0.0027 (8) |
C2 | 0.0378 (7) | 0.0364 (7) | 0.0535 (9) | −0.0114 (6) | −0.0144 (6) | −0.0070 (6) |
C3 | 0.0332 (7) | 0.0372 (7) | 0.0477 (8) | −0.0076 (6) | −0.0108 (6) | −0.0145 (6) |
C4 | 0.0375 (7) | 0.0405 (8) | 0.0473 (8) | −0.0106 (6) | −0.0076 (6) | −0.0136 (6) |
C5 | 0.0570 (10) | 0.0615 (10) | 0.0472 (9) | −0.0235 (8) | −0.0070 (8) | −0.0091 (8) |
C6 | 0.0657 (11) | 0.0873 (14) | 0.0450 (10) | −0.0218 (10) | −0.0056 (8) | −0.0230 (10) |
C7 | 0.0618 (11) | 0.0694 (12) | 0.0637 (12) | −0.0038 (9) | −0.0173 (9) | −0.0399 (10) |
C8 | 0.0431 (8) | 0.0411 (8) | 0.0640 (10) | −0.0028 (7) | −0.0197 (7) | −0.0223 (7) |
C9 | 0.0377 (8) | 0.0469 (8) | 0.0467 (9) | −0.0154 (6) | −0.0054 (6) | −0.0083 (7) |
C10 | 0.0375 (7) | 0.0460 (8) | 0.0458 (8) | −0.0088 (6) | −0.0064 (6) | −0.0135 (7) |
C11 | 0.0578 (10) | 0.0456 (9) | 0.0511 (10) | −0.0148 (8) | −0.0137 (8) | −0.0056 (7) |
C12 | 0.0719 (12) | 0.0498 (10) | 0.0640 (11) | −0.0216 (9) | −0.0160 (9) | −0.0110 (8) |
C13 | 0.0618 (11) | 0.0491 (10) | 0.0826 (14) | −0.0203 (9) | −0.0180 (10) | −0.0054 (9) |
C14 | 0.0510 (9) | 0.0567 (10) | 0.0459 (9) | −0.0181 (8) | −0.0019 (7) | −0.0120 (7) |
C15 | 0.0807 (13) | 0.0597 (11) | 0.0542 (11) | −0.0317 (10) | −0.0108 (9) | −0.0038 (8) |
C16 | 0.126 (2) | 0.0990 (17) | 0.0581 (13) | −0.0693 (17) | 0.0035 (13) | −0.0071 (12) |
N1—H1 | 0.880 (9) | C9—H9B | 0.9700 |
N1—C1 | 1.369 (3) | C9—C10 | 1.524 (2) |
N1—C8 | 1.369 (3) | C10—H10A | 0.9700 |
N2—H2 | 0.980 (9) | C10—H10B | 0.9700 |
N2—C10 | 1.510 (2) | C11—H11A | 0.9700 |
N2—C11 | 1.512 (2) | C11—H11B | 0.9700 |
N2—C14 | 1.502 (2) | C11—C12 | 1.502 (3) |
O1—H1A | 0.856 (10) | C12—H12A | 0.9700 |
O1—C4 | 1.3700 (19) | C12—H12B | 0.9700 |
C1—H1B | 0.9300 | C12—C13 | 1.518 (3) |
C1—C2 | 1.366 (2) | C13—H13A | 0.9600 |
C2—C3 | 1.441 (2) | C13—H13B | 0.9600 |
C2—C9 | 1.501 (2) | C13—H13C | 0.9600 |
C3—C4 | 1.407 (2) | C14—H14A | 0.9700 |
C3—C8 | 1.413 (2) | C14—H14B | 0.9700 |
C4—C5 | 1.382 (2) | C14—C15 | 1.504 (3) |
C5—H5 | 0.9300 | C15—H15A | 0.9700 |
C5—C6 | 1.401 (3) | C15—H15B | 0.9700 |
C6—H6 | 0.9300 | C15—C16 | 1.524 (3) |
C6—C7 | 1.371 (3) | C16—H16A | 0.9600 |
C7—H7 | 0.9300 | C16—H16B | 0.9600 |
C7—C8 | 1.401 (3) | C16—H16C | 0.9600 |
C9—H9A | 0.9700 | ||
C1—N1—H1 | 126.0 (15) | N2—C10—H10A | 108.6 |
C1—N1—C8 | 109.42 (14) | N2—C10—H10B | 108.6 |
C8—N1—H1 | 124.6 (15) | C9—C10—H10A | 108.6 |
C10—N2—H2 | 103.4 (12) | C9—C10—H10B | 108.6 |
C10—N2—C11 | 111.53 (13) | H10A—C10—H10B | 107.6 |
C11—N2—H2 | 105.8 (12) | N2—C11—H11A | 108.8 |
C14—N2—H2 | 108.7 (12) | N2—C11—H11B | 108.8 |
C14—N2—C10 | 114.06 (13) | H11A—C11—H11B | 107.7 |
C14—N2—C11 | 112.56 (13) | C12—C11—N2 | 113.84 (14) |
C4—O1—H1A | 109.4 (16) | C12—C11—H11A | 108.8 |
N1—C1—H1B | 124.9 | C12—C11—H11B | 108.8 |
C2—C1—N1 | 110.22 (16) | C11—C12—H12A | 109.4 |
C2—C1—H1B | 124.9 | C11—C12—H12B | 109.4 |
C1—C2—C3 | 106.02 (15) | C11—C12—C13 | 111.01 (17) |
C1—C2—C9 | 126.16 (16) | H12A—C12—H12B | 108.0 |
C3—C2—C9 | 127.82 (13) | C13—C12—H12A | 109.4 |
C4—C3—C2 | 134.47 (14) | C13—C12—H12B | 109.4 |
C4—C3—C8 | 118.35 (15) | C12—C13—H13A | 109.5 |
C8—C3—C2 | 107.17 (14) | C12—C13—H13B | 109.5 |
O1—C4—C3 | 116.94 (14) | C12—C13—H13C | 109.5 |
O1—C4—C5 | 123.52 (15) | H13A—C13—H13B | 109.5 |
C5—C4—C3 | 119.54 (15) | H13A—C13—H13C | 109.5 |
C4—C5—H5 | 119.8 | H13B—C13—H13C | 109.5 |
C4—C5—C6 | 120.47 (17) | N2—C14—H14A | 108.8 |
C6—C5—H5 | 119.8 | N2—C14—H14B | 108.8 |
C5—C6—H6 | 119.0 | N2—C14—C15 | 113.64 (15) |
C7—C6—C5 | 121.98 (18) | H14A—C14—H14B | 107.7 |
C7—C6—H6 | 119.0 | C15—C14—H14A | 108.8 |
C6—C7—H7 | 121.3 | C15—C14—H14B | 108.8 |
C6—C7—C8 | 117.46 (16) | C14—C15—H15A | 109.6 |
C8—C7—H7 | 121.3 | C14—C15—H15B | 109.6 |
N1—C8—C3 | 107.18 (16) | C14—C15—C16 | 110.23 (18) |
N1—C8—C7 | 130.64 (16) | H15A—C15—H15B | 108.1 |
C7—C8—C3 | 122.18 (17) | C16—C15—H15A | 109.6 |
C2—C9—H9A | 109.6 | C16—C15—H15B | 109.6 |
C2—C9—H9B | 109.6 | C15—C16—H16A | 109.5 |
C2—C9—C10 | 110.36 (12) | C15—C16—H16B | 109.5 |
H9A—C9—H9B | 108.1 | C15—C16—H16C | 109.5 |
C10—C9—H9A | 109.6 | H16A—C16—H16B | 109.5 |
C10—C9—H9B | 109.6 | H16A—C16—H16C | 109.5 |
N2—C10—C9 | 114.75 (12) | H16B—C16—H16C | 109.5 |
N1—C1—C2—C3 | −0.34 (18) | C4—C3—C8—N1 | −178.94 (13) |
N1—C1—C2—C9 | 178.71 (14) | C4—C3—C8—C7 | 0.6 (2) |
N2—C11—C12—C13 | 165.62 (15) | C4—C5—C6—C7 | 0.6 (3) |
N2—C14—C15—C16 | 168.13 (17) | C5—C6—C7—C8 | 0.8 (3) |
O1—C4—C5—C6 | 178.91 (16) | C6—C7—C8—N1 | 178.09 (18) |
C1—N1—C8—C3 | −0.20 (18) | C6—C7—C8—C3 | −1.4 (3) |
C1—N1—C8—C7 | −179.73 (17) | C8—N1—C1—C2 | 0.34 (19) |
C1—C2—C3—C4 | 178.89 (16) | C8—C3—C4—O1 | −179.49 (13) |
C1—C2—C3—C8 | 0.21 (16) | C8—C3—C4—C5 | 0.7 (2) |
C1—C2—C9—C10 | 101.54 (18) | C9—C2—C3—C4 | −0.1 (3) |
C2—C3—C4—O1 | 1.9 (2) | C9—C2—C3—C8 | −178.82 (14) |
C2—C3—C4—C5 | −177.84 (15) | C10—N2—C11—C12 | −168.69 (14) |
C2—C3—C8—N1 | −0.01 (17) | C10—N2—C14—C15 | 61.10 (19) |
C2—C3—C8—C7 | 179.57 (15) | C11—N2—C10—C9 | −72.81 (17) |
C2—C9—C10—N2 | 167.42 (13) | C11—N2—C14—C15 | −170.53 (15) |
C3—C2—C9—C10 | −79.62 (19) | C14—N2—C10—C9 | 56.08 (18) |
C3—C4—C5—C6 | −1.3 (3) | C14—N2—C11—C12 | 61.62 (19) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···Cl1i | 0.88 (1) | 2.40 (1) | 3.2766 (18) | 176 (2) |
N2—H2···Cl1ii | 0.98 (1) | 2.15 (1) | 3.1126 (17) | 169 (2) |
O1—H1A···Cl1 | 0.86 (1) | 2.26 (1) | 3.1068 (15) | 170 (2) |
Symmetry codes: (i) x, y−1, z; (ii) −x+2, −y+1, −z+1. |
Acknowledgements
Financial statements and conflict of interest: This study was funded by CaaMTech, Inc. ARC reports an ownership interest in CaaMTech, Inc., which owns US and worldwide patent applications, covering new tryptamine compounds, compositions, formulations, novel crystalline forms, and methods of making and using the same.
Funding information
Funding for this research was provided by: Division of Chemistry (grant No. CHE-1429086).
References
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