organic compounds
5-MeO-DALT: the freebase of N,N-diallyl-5-methoxytryptamine
aCaaMTech, LLC, 58 East Sunset Way, Suite 209, Issaquah, WA 98027, USA, and bUniversity of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
*Correspondence e-mail: andrew@caam.tech
The title compound {systematic name: N-[2-(5-methoxy-1H-indol-3-yl)ethyl]-N-(prop-2-en-1-yl)prop-2-en-1-amine), C17H22N2O, has a single tryptamine molecule in the The molecules are linked by strong N—H⋯N hydrogen bonds into zigzag chains with graph-set notation C(7) along the [010] direction.
Keywords: crystal structure; tryptamines; indoles; hydrogen bonding.
CCDC reference: 1995802
Structure description
Psychedelics have garnered a great deal of study of late as potential therapeutics for mood disorders (Davis et al., 2020; Carhart-Harris & Goodwin, 2017). Toads in the Bufonidae family release alkaloid secretions when they experience stress. These toads are the genesis of the urban myth of `licking toads' because the secretion contains psychedelic tryptamines. The secretion has contents that can vary greatly from species to species. It is a medley of different chemicals; the skin of the species Bufo alvarius, a desert toad of Arizona, contains a number of indolealkylamines, including bufotenine, O-methylbufotenine, and bufoviridine, among many others (Erspamer et al., 1967).
Recent studies have shown that the psychotropic experiences of inhaling dried toad excretion and that of inhaling pure synthetic O-methylbufotenine [5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT)] are markedly different (Uthaug, Lancelotta, van Oorsouw et al., 2019; Uthaug, Lancelotta, Szabo et al., 2019). The varied experiences suggests that the other tryptamines have significant activity in the psychedelic effects, or that they work in combination through an entourage effect. Accordingly, it is important to understand the pharmacology of not just 5-MeO-DMT, but all of the tryptamines in bufotoxin, and other related molecules.
5-methoxy-N,N-diallyltryptamine (5-MeO-DALT), streetname Foxtrot, is a synthetic analog of O-methylbufotenine first synthesized by Alexander Shulgin in 2004 (Shulgin & Shulgin, 2016). The compound is noted for its quick onset and rapid drop-off, when compared to other psychotropic tryptamines (Corkery et al., 2012), and can cause acute delerium and rhabdomyolysis (Kalasho & Nielsen, 2016). The pharmacology of the compound demonstrates activity at the 5-hydroxytryptamine (5-HT) receptors, particularly 5-HT1A, 5-HT1D, 5-HT2B, 5-HT6, and 5-HT7, though slightly less active at the 5-HT2A receptor, which is believed to be responsible for most psychotropic activity (Cozzi & Daley, 2016). As these molecules become more relevant in the treatment of mood disorders, it will be important to have analytically pure, well-characterized compounds, ideally as crystalline materials. Herein, we report the solid-state structure of 5-methoxy-N,N-diallyltryptamine.
The N,N-diallyltryptamine contains a single tryptamine molecule (Fig. 1). The indole unit is nearly planar with a deviation from planarity of 0.015 Å. The methoxy group is in the same plane, with the indole and methoxy group showing an r.m.s. deviation of only 0.025 Å. The ethylamine group is turned significantly from the indole plane, with a C1—C8—C9—C10 torsion angle of 103.7 (2)°. The molecules are held together by an N1—H1⋯N2 hydrogen bond between the indole N—H and the amino nitrogen atom. These hydrogen bonds join the molecules together along [010] (Table 1). The crystal packing of the title compound is shown in Fig. 2.
of 5-methoxy-The title compound is similar to that of other 5-O-substituted tryptamines whose structures have been reported, including bufotenine (BUFTEN: Falkenberg, 1972a), melatonin (MELATN: Wakahara et al., 1972), 5-MeO-DMT hydrochloride (MOTYPT: Falkenberg & Carlström, 1971), 5-methoxytryptamine (MXTRUP: Quarles et al., 1974), 5-MeO-DMT and 5-methoxymonomethyltryptamine (QQQAGY & QQQAHA: Bergin et al., 1968). The structure is also similar to the freebases of other psychedelic tryptamines that have been reported, including psilocybin (PSILOC: Weber & Petcher, 1974), psilocin (PSILIN: Petcher & Weber, 1974), N,N-dimethyltryptamine (DMTRYP: Falkenberg, 1972b), N-methyl-N-propyltryptamine (WOHYAW: Chadeayne, et al. 2019) and norpsilocin (Chadeayne et al., 2020).
Synthesis and crystallization
Slow evaporation of an acetone solution of a commercial sample (The Indole Shop) of 5-MeO-DALT freebase resulted in the formation of crystals of 5-methoxy-N,N-diallyltryptamine suitable for X-ray analysis.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 1995802
https://doi.org/10.1107/S2414314620004988/bx4017sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620004988/bx4017Isup2.hkl
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).C17H22N2O | F(000) = 584 |
Mr = 270.36 | Dx = 1.177 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 6.1444 (6) Å | Cell parameters from 7918 reflections |
b = 12.8514 (13) Å | θ = 3.2–24.5° |
c = 19.3315 (19) Å | µ = 0.07 mm−1 |
β = 91.626 (3)° | T = 296 K |
V = 1525.9 (3) Å3 | PLATE, colourless |
Z = 4 | 0.3 × 0.1 × 0.03 mm |
Bruker D8 Venture CMOS diffractometer | 2145 reflections with I > 2σ(I) |
φ and ω scans | Rint = 0.068 |
Absorption correction: multi-scan (SADABS; Bruker, 2018) | θmax = 25.5°, θmin = 3.2° |
Tmin = 0.694, Tmax = 0.745 | h = −7→7 |
45375 measured reflections | k = −15→15 |
2810 independent reflections | l = −23→23 |
Refinement on F2 | Hydrogen site location: mixed |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.041 | w = 1/[σ2(Fo2) + (0.0421P)2 + 0.3975P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.106 | (Δ/σ)max < 0.001 |
S = 1.05 | Δρmax = 0.15 e Å−3 |
2810 reflections | Δρmin = −0.13 e Å−3 |
186 parameters | Extinction correction: SHELXL2018 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.036 (4) |
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. |
Refinement. Hydrogen atom H1 was found from a difference-Fourier map and refined isotropically, using a DFIX restrain with an N–H distance of 0.86 (1) Å. The isotropic displacement parameter was set to 1.2Ueq of the parent indolic nitrogen atom. All other hydrogen atoms were placed in calculated positions with appropriate carbon-hydrogen bond lengths: (sp2) 0.93 Å, (CH3) 0.96 Å, (CH2) 0.97 Å. Isotropic displacement parameters were set to 1.2Ueq (C) for sp2 and CH2 parent carbon atoms and 1.5Ueq (C-methyl) |
x | y | z | Uiso*/Ueq | ||
O1 | 0.4047 (2) | 0.31452 (11) | 0.55090 (6) | 0.0675 (4) | |
N1 | 0.0481 (2) | 0.15647 (10) | 0.30952 (7) | 0.0470 (4) | |
N2 | 0.71726 (19) | 0.46740 (9) | 0.22429 (6) | 0.0382 (3) | |
C1 | 0.1988 (3) | 0.18855 (12) | 0.26318 (9) | 0.0459 (4) | |
H1A | 0.192685 | 0.173076 | 0.216165 | 0.055* | |
C2 | 0.1120 (2) | 0.19241 (11) | 0.37388 (8) | 0.0417 (4) | |
C3 | 0.0196 (3) | 0.17930 (13) | 0.43823 (9) | 0.0504 (4) | |
H3 | −0.109406 | 0.142352 | 0.442694 | 0.060* | |
C4 | 0.1243 (3) | 0.22242 (14) | 0.49473 (9) | 0.0541 (5) | |
H4 | 0.064549 | 0.214786 | 0.538107 | 0.065* | |
C5 | 0.3194 (3) | 0.27783 (13) | 0.48877 (9) | 0.0491 (4) | |
C6 | 0.4115 (3) | 0.29288 (12) | 0.42553 (8) | 0.0452 (4) | |
H6 | 0.539720 | 0.330673 | 0.421748 | 0.054* | |
C7 | 0.3063 (2) | 0.24944 (11) | 0.36668 (8) | 0.0392 (4) | |
C8 | 0.3590 (2) | 0.24612 (11) | 0.29497 (8) | 0.0406 (4) | |
C9 | 0.5518 (3) | 0.29470 (12) | 0.26205 (9) | 0.0473 (4) | |
H9A | 0.572877 | 0.262073 | 0.217492 | 0.057* | |
H9B | 0.680614 | 0.281261 | 0.290827 | 0.057* | |
C10 | 0.5280 (2) | 0.41216 (11) | 0.25165 (8) | 0.0389 (4) | |
H10A | 0.404340 | 0.424296 | 0.220377 | 0.047* | |
H10B | 0.493855 | 0.443084 | 0.295809 | 0.047* | |
C11 | 0.9078 (2) | 0.46679 (13) | 0.27223 (8) | 0.0445 (4) | |
H11A | 1.029007 | 0.500425 | 0.250178 | 0.053* | |
H11B | 0.949342 | 0.395345 | 0.281998 | 0.053* | |
C12 | 0.8647 (3) | 0.52092 (13) | 0.33844 (9) | 0.0479 (4) | |
H12 | 0.791552 | 0.584226 | 0.335903 | 0.058* | |
C13 | 0.9215 (3) | 0.48650 (16) | 0.39976 (10) | 0.0649 (5) | |
H13A | 0.994865 | 0.423490 | 0.404413 | 0.078* | |
H13B | 0.888570 | 0.524946 | 0.438859 | 0.078* | |
C14 | 0.7732 (3) | 0.42746 (13) | 0.15593 (8) | 0.0478 (4) | |
H14A | 0.643138 | 0.426748 | 0.126309 | 0.057* | |
H14B | 0.823752 | 0.356257 | 0.160826 | 0.057* | |
C15 | 0.9444 (3) | 0.49012 (14) | 0.12192 (9) | 0.0540 (5) | |
H15 | 0.939074 | 0.562062 | 0.126783 | 0.065* | |
C16 | 1.0998 (4) | 0.45147 (19) | 0.08615 (11) | 0.0799 (7) | |
H16A | 1.110188 | 0.379848 | 0.080213 | 0.096* | |
H16B | 1.201163 | 0.495318 | 0.066365 | 0.096* | |
C17 | 0.6043 (4) | 0.36914 (19) | 0.54980 (11) | 0.0765 (6) | |
H17A | 0.641883 | 0.393335 | 0.595580 | 0.115* | |
H17B | 0.589963 | 0.427531 | 0.519037 | 0.115* | |
H17C | 0.716441 | 0.323651 | 0.534050 | 0.115* | |
H1 | −0.053 (3) | 0.1114 (13) | 0.3001 (11) | 0.092* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0743 (9) | 0.0789 (9) | 0.0489 (8) | 0.0010 (7) | −0.0049 (6) | −0.0074 (6) |
N1 | 0.0463 (8) | 0.0388 (8) | 0.0558 (9) | −0.0055 (6) | −0.0007 (6) | −0.0011 (6) |
N2 | 0.0355 (6) | 0.0353 (7) | 0.0437 (7) | −0.0011 (5) | 0.0004 (5) | −0.0024 (5) |
C1 | 0.0538 (9) | 0.0367 (8) | 0.0475 (9) | 0.0008 (7) | 0.0026 (7) | −0.0016 (7) |
C2 | 0.0418 (8) | 0.0321 (8) | 0.0511 (9) | 0.0035 (6) | 0.0001 (7) | 0.0027 (7) |
C3 | 0.0470 (9) | 0.0445 (9) | 0.0600 (11) | 0.0000 (7) | 0.0077 (8) | 0.0084 (8) |
C4 | 0.0584 (11) | 0.0562 (10) | 0.0481 (10) | 0.0097 (8) | 0.0087 (8) | 0.0089 (8) |
C5 | 0.0527 (10) | 0.0472 (9) | 0.0470 (10) | 0.0095 (8) | −0.0031 (8) | −0.0005 (7) |
C6 | 0.0432 (8) | 0.0380 (8) | 0.0542 (10) | 0.0029 (7) | −0.0008 (7) | −0.0010 (7) |
C7 | 0.0394 (8) | 0.0299 (7) | 0.0482 (9) | 0.0045 (6) | 0.0011 (7) | 0.0017 (6) |
C8 | 0.0430 (8) | 0.0284 (7) | 0.0505 (9) | 0.0037 (6) | 0.0036 (7) | 0.0001 (6) |
C9 | 0.0470 (9) | 0.0369 (9) | 0.0586 (10) | 0.0028 (7) | 0.0113 (8) | 0.0011 (7) |
C10 | 0.0342 (8) | 0.0364 (8) | 0.0459 (9) | 0.0010 (6) | 0.0001 (6) | 0.0000 (6) |
C11 | 0.0359 (8) | 0.0437 (9) | 0.0537 (10) | −0.0013 (7) | −0.0023 (7) | −0.0043 (7) |
C12 | 0.0481 (9) | 0.0401 (9) | 0.0552 (10) | −0.0033 (7) | −0.0054 (8) | −0.0054 (7) |
C13 | 0.0702 (13) | 0.0677 (12) | 0.0559 (11) | 0.0061 (10) | −0.0122 (9) | −0.0051 (9) |
C14 | 0.0490 (9) | 0.0482 (9) | 0.0465 (9) | −0.0083 (7) | 0.0035 (7) | −0.0048 (7) |
C15 | 0.0577 (11) | 0.0540 (10) | 0.0505 (10) | −0.0133 (8) | 0.0043 (8) | −0.0003 (8) |
C16 | 0.0770 (14) | 0.0871 (15) | 0.0769 (14) | −0.0315 (12) | 0.0275 (12) | −0.0193 (12) |
C17 | 0.0753 (14) | 0.0892 (16) | 0.0639 (13) | −0.0017 (12) | −0.0156 (10) | −0.0125 (11) |
O1—C5 | 1.380 (2) | C9—H9B | 0.9700 |
O1—C17 | 1.414 (2) | C9—C10 | 1.529 (2) |
N1—C1 | 1.370 (2) | C10—H10A | 0.9700 |
N1—C2 | 1.374 (2) | C10—H10B | 0.9700 |
N1—H1 | 0.863 (5) | C11—H11A | 0.9700 |
N2—C10 | 1.4735 (18) | C11—H11B | 0.9700 |
N2—C11 | 1.4726 (19) | C11—C12 | 1.487 (2) |
N2—C14 | 1.4677 (19) | C12—H12 | 0.9300 |
C1—H1A | 0.9300 | C12—C13 | 1.303 (2) |
C1—C8 | 1.364 (2) | C13—H13A | 0.9300 |
C2—C3 | 1.392 (2) | C13—H13B | 0.9300 |
C2—C7 | 1.411 (2) | C14—H14A | 0.9700 |
C3—H3 | 0.9300 | C14—H14B | 0.9700 |
C3—C4 | 1.369 (2) | C14—C15 | 1.492 (2) |
C4—H4 | 0.9300 | C15—H15 | 0.9300 |
C4—C5 | 1.402 (2) | C15—C16 | 1.294 (3) |
C5—C6 | 1.375 (2) | C16—H16A | 0.9300 |
C6—H6 | 0.9300 | C16—H16B | 0.9300 |
C6—C7 | 1.408 (2) | C17—H17A | 0.9600 |
C7—C8 | 1.433 (2) | C17—H17B | 0.9600 |
C8—C9 | 1.497 (2) | C17—H17C | 0.9600 |
C9—H9A | 0.9700 | ||
C5—O1—C17 | 117.69 (15) | N2—C10—C9 | 116.70 (12) |
C1—N1—C2 | 108.04 (13) | N2—C10—H10A | 108.1 |
C1—N1—H1 | 123.8 (15) | N2—C10—H10B | 108.1 |
C2—N1—H1 | 127.0 (15) | C9—C10—H10A | 108.1 |
C11—N2—C10 | 113.15 (12) | C9—C10—H10B | 108.1 |
C14—N2—C10 | 111.23 (12) | H10A—C10—H10B | 107.3 |
C14—N2—C11 | 111.24 (12) | N2—C11—H11A | 109.1 |
N1—C1—H1A | 124.4 | N2—C11—H11B | 109.1 |
C8—C1—N1 | 111.17 (14) | N2—C11—C12 | 112.40 (13) |
C8—C1—H1A | 124.4 | H11A—C11—H11B | 107.9 |
N1—C2—C3 | 130.91 (15) | C12—C11—H11A | 109.1 |
N1—C2—C7 | 107.83 (14) | C12—C11—H11B | 109.1 |
C3—C2—C7 | 121.25 (15) | C11—C12—H12 | 117.5 |
C2—C3—H3 | 121.0 | C13—C12—C11 | 125.04 (17) |
C4—C3—C2 | 118.00 (16) | C13—C12—H12 | 117.5 |
C4—C3—H3 | 121.0 | C12—C13—H13A | 120.0 |
C3—C4—H4 | 119.2 | C12—C13—H13B | 120.0 |
C3—C4—C5 | 121.57 (16) | H13A—C13—H13B | 120.0 |
C5—C4—H4 | 119.2 | N2—C14—H14A | 108.9 |
O1—C5—C4 | 113.98 (15) | N2—C14—H14B | 108.9 |
C6—C5—O1 | 124.76 (16) | N2—C14—C15 | 113.21 (13) |
C6—C5—C4 | 121.26 (16) | H14A—C14—H14B | 107.7 |
C5—C6—H6 | 120.9 | C15—C14—H14A | 108.9 |
C5—C6—C7 | 118.12 (15) | C15—C14—H14B | 108.9 |
C7—C6—H6 | 120.9 | C14—C15—H15 | 117.7 |
C2—C7—C8 | 107.18 (13) | C16—C15—C14 | 124.64 (18) |
C6—C7—C2 | 119.78 (14) | C16—C15—H15 | 117.7 |
C6—C7—C8 | 133.00 (14) | C15—C16—H16A | 120.0 |
C1—C8—C7 | 105.77 (13) | C15—C16—H16B | 120.0 |
C1—C8—C9 | 127.18 (15) | H16A—C16—H16B | 120.0 |
C7—C8—C9 | 127.04 (14) | O1—C17—H17A | 109.5 |
C8—C9—H9A | 108.9 | O1—C17—H17B | 109.5 |
C8—C9—H9B | 108.9 | O1—C17—H17C | 109.5 |
C8—C9—C10 | 113.19 (13) | H17A—C17—H17B | 109.5 |
H9A—C9—H9B | 107.8 | H17A—C17—H17C | 109.5 |
C10—C9—H9A | 108.9 | H17B—C17—H17C | 109.5 |
C10—C9—H9B | 108.9 | ||
O1—C5—C6—C7 | 179.25 (14) | C3—C4—C5—C6 | 1.3 (3) |
N1—C1—C8—C7 | 0.67 (17) | C4—C5—C6—C7 | −1.1 (2) |
N1—C1—C8—C9 | 179.97 (14) | C5—C6—C7—C2 | 0.0 (2) |
N1—C2—C3—C4 | 178.16 (16) | C5—C6—C7—C8 | −177.13 (15) |
N1—C2—C7—C6 | −178.18 (13) | C6—C7—C8—C1 | 177.21 (16) |
N1—C2—C7—C8 | −0.40 (16) | C6—C7—C8—C9 | −2.1 (3) |
N2—C11—C12—C13 | 135.82 (18) | C7—C2—C3—C4 | −0.8 (2) |
N2—C14—C15—C16 | 140.91 (19) | C7—C8—C9—C10 | −77.2 (2) |
C1—N1—C2—C3 | −178.24 (16) | C8—C9—C10—N2 | 175.60 (13) |
C1—N1—C2—C7 | 0.80 (17) | C10—N2—C11—C12 | −62.30 (17) |
C1—C8—C9—C10 | 103.67 (18) | C10—N2—C14—C15 | 172.28 (13) |
C2—N1—C1—C8 | −0.94 (18) | C11—N2—C10—C9 | −65.85 (17) |
C2—C3—C4—C5 | −0.3 (2) | C11—N2—C14—C15 | −60.60 (18) |
C2—C7—C8—C1 | −0.16 (16) | C14—N2—C10—C9 | 60.23 (18) |
C2—C7—C8—C9 | −179.46 (14) | C14—N2—C11—C12 | 171.63 (13) |
C3—C2—C7—C6 | 1.0 (2) | C17—O1—C5—C4 | 178.50 (16) |
C3—C2—C7—C8 | 178.75 (14) | C17—O1—C5—C6 | −1.8 (2) |
C3—C4—C5—O1 | −178.99 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···N2i | 0.86 (1) | 2.15 (1) | 2.9880 (18) | 162 (2) |
Symmetry code: (i) −x+1/2, y−1/2, −z+1/2. |
Acknowledgements
Financial statements and conflict of interest: This study was funded by CaaMTech, Inc. ARC reports an ownership interest in 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: National Science Foundation, Directorate for Mathematical and Physical Sciences (grant No. CHE-1429086).
References
Bergin, R., Carlström, D., Falkenberg, G. & Ringertz, H. (1968). Acta Cryst. B24, 882. CSD CrossRef IUCr Journals Google Scholar
Bruker (2018). APEX3, SAINT, and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Carhart-Harris, R. L. & Goodwin, G. M. (2017). Neuropsychopharmacology, 42, 2105–2113. Web of Science CAS PubMed Google Scholar
Chadeayne, A. R., Golen, J. A. & Manke, D. R. (2019). IUCrData, 4, x190962. Google Scholar
Chadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2020). Acta Cryst. E76, 589–593. CSD CrossRef IUCr Journals Google Scholar
Corkery, J. M., Durkin, E., Elliott, S., Schifano, F. & Ghodse, A. H. (2012). Prog. Neuropsychopharmacol. Biol. Psychiatry, 39, 259–262. CrossRef CAS PubMed Google Scholar
Cozzi, N. V. & Daley, P. F. (2016). Bioorg. Med. Chem. Lett. 26, 959–964. CrossRef CAS PubMed Google Scholar
Davis, A. K., Barrett, F. S. & Griffiths, R. R. (2020). J. Contextual Behav. Sci. 15, 39–45. CrossRef Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Erspamer, V., Vitali, T., Roseghini, M. & Cei, J. M. (1967). Biochem. Pharmacol. 16, 1149–1164. CrossRef CAS PubMed Google Scholar
Falkenberg, G. (1972a). Acta Cryst. B28, 3075–3083. CSD CrossRef IUCr Journals Web of Science Google Scholar
Falkenberg, G. (1972b). Acta Cryst. B28, 3219–3228. CSD CrossRef IUCr Journals Web of Science Google Scholar
Falkenberg, G. & Carlström, D. (1971). Acta Cryst. B27, 411–418. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
Kalasho, A. & Nielsen, S. V. (2016). Acta Anaesthesiol. Scand. 60, 1332–1336. CrossRef CAS PubMed Google Scholar
Petcher, T. J. & Weber, H. P. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 946–948. CSD CrossRef Web of Science Google Scholar
Quarles, W. G., Templeton, D. H. & Zalkin, A. (1974). Acta Cryst. B30, 95–98. CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shulgin, A. T. & Shulgin, A. (2016). TiKHAL: The Continuation. Isomerdesign. Available at: https://isomerdesign.com/PiHKAL/read.php?domain=tk&id=56. Accessed 19 March 2020. Google Scholar
Uthaug, M. V., Lancelotta, R., Szabo, A., Davis, A. K., Riba, J. & Ramaekers, J. G. (2019). Psychpharmacology 237, 773-785. CrossRef Google Scholar
Uthaug, M. V., Lancelotta, R., van Oorsouw, K., Kuypers, K. P. C., Mason, N., Rak, J., Šuláková, A., Jurok, R., Maryška, M., Kuchař, M., Páleníček, T., Riba, J. & Ramaekers, J. G. (2019). Psychopharmacology, 236, 2653–2666. CrossRef CAS PubMed Google Scholar
Wakahara, A., Fujiwara, T. & Tomita, K. (1972). Chem. Lett. 1, 1139–1142. CSD CrossRef Google Scholar
Weber, H. P. & Petcher, T. J. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 942–946. CSD CrossRef Web of Science Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
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