468
A. M. Abou-Douh et al. · Prenylated Flavonoids from the Root of Egyptian Tephrosia apollinea
HSQC experiments, see Table 1. -13C NMR: The 13C attribu- and HSQC experiments, see Table 1. -13C NMR: The 13C
tions were achieved by HSQC and HMBC experiments, see attributions were achieved by HSQC and HMBC experi-
Tables 2 and 3. – HR-MS: m/z 392.1260 [M+] (C23H20O6 ments, see Tables 2 and 3. – HR-MS: m/z 336.1362 [M+]
requires 392.1258). – MS (EI, 70 eV): m/z (%) = 392(16) (C21H20O4 requires 336.1360). – MS (EI, 70 eV): The data
[M+], 332(100), 317(38), 303(19), 289(31), 263 (26), 230 are in agreement with those reported in the literature [12].
(15), 160 (18), 102 (9) and 43 (65) [9].
X-ray crystallographic analysis for compounds 1 and 5 [24]
(-)-Semiglabrinol; 2ꢀꢀꢀ,2ꢀꢀꢀ-dimethyl-3ꢀꢀꢀ-hydroxy-tetrahydro-
Crystal data for compound 1
furano-[3ꢀꢀ,2ꢀꢀ-b]-dihydrofurano [5ꢀꢀ,4ꢀꢀ-h]-flavone (2)
C23H20O6; MW 392.39, orthorhombic, space group
Compound 1 (20 mg) was dissolved in the minimum
amount of 0.1% KOH and allowed to stand for 24 h. The
mixture was diluted with H2O and exited with CH2Cl2 to
P212121 (D42) no. 19 from Laue symmetry and systematic
absences: h00 when h = 2n, 0k0 when k = 2n, 00l when
˚
˚
˚
l = 2n; a = 6.719 (2) A, b = 12.725 (3) A, c = 21.789 (6) A,
give a colourless oil. Crystallization from Me2CO gave 2
as a white needles (15 mg), m.p. 247 – 249 ◦C, [α]D25 −266◦
(c0.10, CHCl3). – UV (MeOH): λmax = 308, 255, 243 (sh)
V = 1862.9 (9) A , Z = 4, Dc = 1.399 g cm−3, µ(Mo-Kα
3
˚
radiation) = 0.101 mm−1; crystal dimensions: 0.72×0.12×
0.06 mm, see Table 4.
˜
and 211 nm . – IR (KBr): ν = 3350 (OH), 1635 (γ-pyrone
CO) and 1600 cm−1 (C=C). -1H and -13C NMR spectra of
this compound were in agreement with the data reported for
natural (-)-semiglabrinol [23], see Tables 1 and 2. – MS (EI,
70 eV): m/z (%) = 350 (33) [M+], 332 (100), 317 (46),
289 (30), 263 (35), 230 (19), 160 (25), 149 (34), 103 (16)
and 43 (30).
Crystal data for compound 5
C
21H20O4; MW 336.37, monoclinic, space group P21/c
(C52h) no. 14 from Laue symmetry and systematic absences:
h0l when l = 2n, 0k0 when k = 2n, 00l when l = 2n, a =
˚
˚
˚
7.3441 (3) A, b = 11.310 (1) A, c = 20.573 (2) A, β−=3
◦
3
˚
90.377 (5) , V = 1708.8 (2) A , Z = 4, Dc = 1.307 g cm
,
(-)-Pseudosemiglabrin (3)
µ(Cu-Kα radiation) = 0.730 mm−1; crystal dimensions:
0.56×0.18×0.18 mm, see Table 4.
C
23H20O6; crystallized from MeOH as colourless prisms,
◦
m. p. 169 – 171 C, [α]D25 − 379◦ (c0.90, CHCl3). -UV and
Unit cell parameters were obtained by least-squares fit
of 35 (20 < θ < 25◦ for compound 1, 50 < θ < 56◦ for
compound 5) accurately centered reflections. Intensity data
(3261+h, +k, +l plus Friedel pairs reflections for 1, 2275+
-IR were identical to 1. – 1H NMR: The 1H assignments
were achieved by H–1H correlation spectroscopy (COSY)
1
and HSQC experiments, see Table 1. – 13C NMR: The 13C
attributions were achieved by HSQC and HMBC experi-
ments, see Tables 2 and 3. – HR-MS: m/z 392.1258 [M+]
(C23H20O6 requires 392.1256). – MS (EI, 70 eV): The data
were similar to that of compound 1.
◦
h, +k, l reflections for 5) were recorded at 25 C on a
Siemens P4/PC diffractometer [Mo-Kα radiation for 1, Cu-
Kα for 5, graphite monochromator, ω-2θ scans, θmax = 25◦
for 1, θmax = 56.75◦ for 5]. The intensities of three reference
reflections, monitored every 97 measurements during data
collection, showed no significant variation (< 3%) through-
out. The usual Lorentz and polarization corrections were ap-
plied to intensity data and all the data were used for the struc-
ture refinement.
(-)-Pseudosemiglabrinol (4)
Mild alkaline hydrolysis of compound 3, 15 mg as men-
tioned above gave 4 as white needles from Me2CO (12 mg),
m.p. 268 – 269 C, [α]D25 − 255◦ (c0.50, CHCl3). -UV and
◦
Both crystal structures were solved by direct methods
(SIR 92) [25]. Initial coordinates for all nonhydrogen atoms
were obtained from E-maps. The enantiomer in case of
structure of (-)-semiglabrin was chosen to yield the same
stereochemistry at C-2ꢀꢀ and C-3ꢀꢀ as in 1. Positional and
thermal parameters of these atoms (first isotropic and then
anisotropic) were adjusted by means of several rounds
of full-matrix least-squares calculations [26] during which
-IR were identical to 2. -1H and -13C NMR spectra of this
compound were in agreement with the data reported for nat-
ural (-)-pseudosemiglabrinol [23], see Tables 1 and 2. – MS
(EI, 70 eV): The data were similar to those of compound 2.
Lanceolatin A; 7-methoxy-8-(3ꢀꢀ-hydroxy-3ꢀꢀ-methyl-trans-
isobut-1ꢀꢀ-enyl)-flavone (5)
C
21H20O4; crystallized from MeOH as colourless pris- Σ(w|Fo2 − Fc2|)2, with w = 1/[σ2(Fo2) + (0.0269P)2] for 1
◦
matic needles, m. p. 186 – 188 C. – UV (MeOH): λmax
=
and, w = 1/[σ2(Fo2) + (0.0574P)2 + 0.2638P] for 5. All the
˜
318, 262, 224 nm. – IR (KBr): ν = 3500, 1384, 1149 (ter. hydrogen atoms were included as fixed contributions and
OH), 1635,1590 (γ-pyrone CO and styryl), 1410, 1265, 970, not refined. Their idealized positions were generated from
815, 780 and 710 cm−1. -1H NMR: The 1H assignments the geometries about the attached carbon atoms, and forced
were achieved by H–1H correlation spectroscopy (COSY) to ride on it with a fixed isotropic temperature factor, U =
1
Unauthenticated
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