research papers
Table 1
Experimental details.
For all structures: C21H24BrNO3, Mr = 418.32, Z = 8. Experiments were carried out at 100 K with Mo Kꢁ radiation using a Bruker SMART BREEZE CCD area-
detector diffractometer. Absorption was corrected for by multi-scan methods (SADABS; Bruker, 2008). H atoms were treated by a mixture of independent and
constrained refinement.
(I)
(II)
(III)
Crystal data
Crystal system, space group
Orthorhombic, Pbcn
18.0371 (4), 15.4309 (3), 14.2604 (3)
90, 90, 90
3969.08 (14)
2.09
Orthorhombic, Pbcn
17.0813 (5), 15.4877 (5), 14.2544 (5)
90, 90, 90
3771.0 (2)
2.20
Monoclinic, P21/c
14.5012 (18), 18.299 (2), 15.1952 (19)
90, 107.5262 (15), 90
3844.9 (8)
2.16
0.34 ꢃ 0.16 ꢃ 0.08
˚
a, b, c (A)
ꢁ, ꢂ, ꢃ (ꢁ)
3
˚
V (A )
ꢄ (mmꢂ1
Crystal size (mm)
)
0.26 ꢃ 0.18 ꢃ 0.13
0.40 ꢃ 0.21 ꢃ 0.19
Data collection
Tmin, Tmax
0.909, 1.000
35271, 4558, 3391
0.839, 1.000
55070, 5055, 4278
0.866, 1.000
45465, 8935, 6859
No. of measured, independent and
observed [I > 2ꢅ(I)] reflections
Rint
0.038
0.650
0.032
0.684
0.065
0.653
ꢂ1
˚
(sin ꢆ/ꢇ)max (A
)
Refinement
R[F2 > 2ꢅ(F2)], wR(F2), S
No. of reflections
No. of parameters
0.042, 0.101, 1.04
4558
243
1.49, ꢂ1.21
0.032, 0.084, 1.03
5055
243
1.31, ꢂ0.38
0.036, 0.081, 1.02
8935
485
ꢂ3
˚
Áꢈmax, Áꢈmin (e A
)
1.46, ꢂ0.47
Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and OLEX2 (Dolomanov et al., 2009).
bromobenzaldehyde (1.0 g, 5.405 mmol) and a quantity of
ammonium acetate (0.419 g) were added to the stirred solu-
tion, and stirring was continued at room temperature for a
further 48 h. The progress of the reaction was monitored via
thin-layer chromatography (TLC). Once the reaction was
complete, excess solvent was removed via rotary evaporation.
The solution was then purified via silica-column chromato-
graphy. The products were recrystallized from hexane and
ethyl acetate (1:4 v/v) as white to light-yellow crystalline solids
[for (I): yield 1.91 g, 4.57 mmol, 84.00%; for (II): yield 1.86 g,
4.45 mmol, 82.30%; for (III): yield 1.45 g, 3.466 mmol,
63.76%]. Analytical samples of the products were again re-
crystallized from a minimum of warm hexane and ethyl
acetate (1:4 v/v), to which hexane was added dropwise to a
faint opalescence, and slow evaporation produced diffraction-
quality crystals as white to light-yellow crystalline solids.
29.44, 27.15, 19.49, 14.23. HRMS calculated for C21H24BrNO3:
418.1018; found: 418.1024. MS, m/z = 418 ([M + 1] 100), 419
([M + 2] 10), 420 ([M + 3] 100). M.p. 527–528 K. TLC [SiO2,
hexane–EtOAc (3:2 v/v)]: RF = 0.19.
Compound (II). 1H NMR (CDCl3): ꢀ 7.41 (s, 1H), 7.26 (d, J=
7.53 Hz, 1H), 7.22 (d, J = 8.53 Hz, 1H), 7.07 (t, J = 7.78 Hz, 1H),
6.09 (bs, 1H), 5.03 (s, 1H), 4.07 (m, J = 7.15 Hz, 2H), 2.38 (s,
3H), 2.31 (s, 2H), 2.22 (s, 2H), 1.21 (t, J = 7.15 Hz, 3H), 1.09 (s,
3H), 0.96 (s, 6H); 13C NMR (CDCl3): ꢀ 195.39, 167.15, 149.30,
148.24, 143.79, 131.09, 129.17, 126.97, 122.10, 111.71, 105.60,
59.96, 50.69, 41.12, 36.64, 32.78, 29.40, 27.22, 19.51, 14.21.
HRMS calculated for C21H24BrNO3: 418.1018; found:
418.0979. MS, m/z = 418 ([M + 1] 100), 419 ([M + 2] 90). M.p.
508–509 K. TLC [SiO2, hexane–EtOAc (3:2 v/v)]: RF = 0.12.
Compound (III). 1H NMR (CDCl3): ꢀ 7.44 (dd, J = 7.91 Hz,
1H), 7.37 (dd, J = 7.78 Hz, 1H), 7.16 (tt, J = 7.53 Hz, 1H), 6.94
(tt, J = 7.91 Hz, 1H), 5.92 (bs, 1H), 5.37 (s, 1H), 4.08 (m, J =
7.15 Hz, 2H), 2.32 (s, 3H), 2.30 (s, 2H), 2.19 (s, 2H), 1.18 (t, J =
7.03 Hz, 3H), 1.08 (s, 3H), 0.96 (s, 6H); 13C NMR (CDCl3): ꢀ
195.30, 167.44, 148.04, 145.88, 143.22, 133.08, 132.03, 127.49,
126.97, 123.38, 111.74, 105.86, 59.84, 50.69, 41.29, 37.98, 32.58,
29.28, 27.38, 19.49, 14.36. HRMS calculated for C21H24BrNO3:
418.1018; found: 418.1037. MS: m/z = 417 ([M] 100), 418
([M + 1] 100), 419 ([M + 2] 30). M.p. 473–477 K. TLC [SiO2,
hexane–EtOAc (3:2 v/v)]: RF = 0.23.
2.2. Characterization information
Melting points were determined in open capillary tubes
with a Mel-Temp melting point apparatus (200 W) and are
uncorrected. Structures were confirmed with 1H and 13C NMR,
1
and mass spectroscopy. H NMR spectra were obtained in
chloroform-d1 using a Bruker AMX 400 MHz spectrometer.
Chemical shifts are reported as p.p.m. relative to tetra-
methylsilane (TMS). LC–MS (liquid chromatography–mass
spectrometry) data were obtained using a Waters LCT
Premier XE series spectrometer.
2.3. Refinement
1
Compound (I). H NMR (CDCl3): ꢀ 7.31 (d, J = 8.28 Hz,
Crystal data, data collection and structure refinement
details are summarized in Table 1. The methyl H atoms were
˚
constrained to an ideal geometry, with C—H = 0.98 A and
Uiso(H) = 1.5Ueq(C), and were allowed to rotate freely about
their C—C bonds. The remaining C-bound H atoms were
˚
placed in calculated positions, with C—H = 0.95–1.00 A, and
2H), 7.20 (d, J = 8.28 Hz, 2H), 6.01 (bs, 1H), 5.02 (s, 1H), 4.05
(q, J = 7.03 Hz, 2H), 2.38 (s, 3H), 2.21 (s, 2H), 2.17 (s, 2H), 1.20
(t, J = 7.15 Hz, 3H), 1.08 (s, 3H), 0.93 (s, 6H); 13C NMR
(CDCl3): ꢀ 195.42, 167.19, 148.01, 146.07, 143.60, 130.96,
129.89, 119.82, 111.90, 105.72, 59.94, 50.69, 41.14, 36.33, 32.75,
ꢀ
Acta Cryst. (2014). C70, 790–795
Steiger et al.
Three homologues of C21H24BrNO3 791