°
distorted boat ( 0.076 A) with C14 and C21 deviating from the plane of the remaining four atoms. Ring E took the
°
°
6ꢀ-envelope shape ( 0.016 A) with C6 deviating from the plane of the remaining atoms by 0.665 A.
The geometry of 3 in the salt form (methylated at N4) was distorted from that observed in base 2 (Fig. 1). The bond
lengths and angles of 3 could not be compared with those observed in 2 because of poor statistics (large uncertainties).
However, conformational changes in 3 could be noticed. For example, ring D in 3 adopted a slightly distorted chair conformation
although in 2 and in all previously examined fluorocurarine frameworks it typically adopted the boat conformation [1, 6–8].
°
°
The placement of the benzene ring ( 0.004 A) joined through the C23–N2 bond to the pseudo-aromatic system ( 0.006 A)
also differed from that observed in 2. It was situated at an angle of 75.9° relative to the heteroaromatic system. Ring E in 3 had
°
°
the Nꢂ-envelope shape ( 0.017 A) with N4 deviating from the plane of the remaining atoms by 0.630 A, which differed from
°
that observed in 2. However, ring C retained its half-chair conformation with C14 deviating by 0.680 A from the plane of the
°
other five atoms ( 0.001 A).
In conclusion, we note that the conformation change of five-membered ring E after methylation of N4 in the salt
caused a change from the 6ꢀ-envelope (2) to the N4ꢂ-envelope (3). This changed the mutual position of the C5 and C6
protons, which explained easily the anomalous locations of the resonances for these protons in the PMR spectra [9].
The packing of 2 in the crystal exhibited a weak intermolecular interaction between N4 of the initial molecule and an
°
NH H atom of the molecule translated along the a axis [–1 + x, y, z] with parameters N4…N1 3.153(2), N4…H 2.34 A, and
2
N4…H–N1 152°. The iodide atom in 3 also approached an NH H atom, forming a H-bond with parameters 4.01(2), 3.18, and
2
163, respectively.
EXPERIMENTAL
IR spectra were recorded in KBr pellets on a PerkinElmer Model 2000 Fourier IR spectrometer. UV spectra were
measured on a PerkinElmer Lambda-16 spectrophotometer.
Compound 2. Norfluorocurarine hydrochloride (2.94 g) with one water of crystallization was dissolved in hot water
(100 mL), treated with an aqueous solution (30 mL) of phenylhydrazine hydrochloride (1.7 g), heated on a water bath for 1 h,
cooled, made basic with aqueous NaOH (10%), and extracted with Et O. The Et O extract was dried over anhydrous Na SO
2
2
2
4
and condensed. The resulting crystals (1.08 g) were separated and recrystallized from Me CO, mp 177–178°C, C H N ,
2
25 26 4
20
[ꢀ] –192.3° (c 1.258, MeOH). TLC R 0.60 (CHCl :MeOH, 1:1). UV spectrum (ꢋ , nm, log ꢌ): 240.7 (4.02), 294.07
(3.22). IR spectrum (ꢍ , cm ): 3452, 3315, 3195 (NH ), 1956 (NH ), 1634 (C=N), 1310 (=N–).
D
f
3
max
–1
max
2
2
Compound 2 Hydrochloride. Norfluorocurarine hydrochloride (1 g) with one water of crystallization was dissolved
in H O (100 mL), treated with phenylhydrazine sulfate (0.9 g) dissolved in H O (20 mL), heated on a boiling-water bath for
2
2
1 h, and evaporated in vacuo after adding EtOH (100 mL). The solid was stirred with hot water (20 mL). The crystals were
20
separated. Yield 1.61 g, mp 285–286°C (aqueous EtOH), C H N Cl, [ꢀ] –142.29° (c 1.962, MeOH). The base was
25 27
4
D
obtained by the usual method from the hydrochloride (1.61 g). Under analogous conditions, anhydrous norfluorocurarine
hydrochloride (3 g, mp 220–221°C) and phenylhydrazine hydrochloride (1.5 g) afforded 2 (1.87 g).
Methyliodide of 2. Compound 2 (640 mg) was dissolved in MeOH (3 mL), treated with methyliodide (0.5 mL),
heated on a boiling-water bath for 30 min, and condensed. Crystals of 3 (700 mg) formed, mp 292–293°C, C H H I.
26 29
4
X-ray Crystal Structure Analyses (XSA). Single crystals of 2 and 3 for the XSA were grown by slow evaporation
from aqueous alcohol at room temperature. Unit-cell constants for crystals of 2 were determined and refined on an Xcalibur
Ruby CCD diffractometer (Oxford Diffraction) using Cu Kꢀ-radiation (300 K, graphite monochromator) [10]. A three-
dimensional dataset of reflections was obtained on the same diffractometer. The XSA of a crystal of 3 was performed on a
STOE Stadi-4 four-circle diffractometer using Cu Kꢀ-radiation (300 K, graphite monochromator, ꢉ/2ꢉ-scanning). Absorption
corrections were applied in both instances by a semi-empirical methods using the SADABS program [11]. Table 1 presents the
principal parameters of the XSA and refinement calculations for 2 and 3.
The structures were solved by direct methods using the SHELXS-97 software. The structures were refined using the
SHELXL-97 program. Graphics were plotted using the SHELXTL program [12]. All non-hydrogen atoms were refined by a
2
full-matrix anisotropic least-squares method (over F ). Positions of H atoms were found geometrically and refined with fixed
isotropic thermal parameters U = nU , where n = 1.5 for methyls and 1.2 for others and U is the equivalent isotropic
iso
eq
eq
thermal parameter of the corresponding C atom. H atoms of the NH group in 2 were found in a difference electron-density
2
synthesis.
627
Tashkhodzhaev
