(E)-2-Hy-droxy-4-meth-oxy-3-(3-methyl-but-2-en-yl)-6-styryl-benzoic acid.

The title compound, C21H22O4, also known as cajanine, features an intra-molecular O-H⋯O hydrogen bond between the adjacent carb-oxy and hy-droxy groups. The benzene rings make an inter-planar angle of 175.4 (2)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers.

Related literature

Cajanine is an important component of the herb Cajanus cajan L., which is used in traditional Chinese medicine to treat osteonecrosis of the femoral head. For the total synthesis of cajanine, see: Ji et al. (2011 ▶). For the bioactivity of cajanine, see: Fu et al. (2009 ▶); Ji et al. (2011 ▶); Luo et al. (2008a ▶,b ▶); Zheng et al. (2007a ▶,b ▶); Inman & Hopp (2002 ▶); Ruan et al. (2009 ▶).

Experimental

Crystal data

C21H22O4

M = 338.39

Triclinic,

a = 6.9790 (3) Å

b = 9.9975 (8) Å

c = 13.8202 (11) Å

α = 77.899 (1)°

β = 78.956 (2)°

γ = 78.507 (2)°

V = 912.58 (11) Å3

Z = 2

Mo Kα radiation

μ = 0.08 mm−1

T = 298 K

0.35 × 0.32 × 0.31 mm

Data collection

Bruker SMART APEX diffractometer

4547 measured reflections

3138 independent reflections

1735 reflections with I > 2σ(I)

R int = 0.024

Refinement

R[F 2 > 2σ(F 2)] = 0.052

wR(F 2) = 0.152

S = 1.06

3138 reflections

229 parameters

H-atom parameters constrained

Δρmax = 0.15 e Å−3

Δρmin = −0.18 e Å−3

Data collection: SMART (Bruker, 1999 ▶); cell refinement: SAINT (Bruker, 1999 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick 2008 ▶); software used to prepare material for publication: SHELXTL.

Click here for additional data file.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812050258/ng5309sup1.cif

Click here for additional data file.

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812050258/ng5309Isup2.hkl

Click here for additional data file.

Supplementary material file. DOI: 10.1107/S1600536812050258/ng5309Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C21H22O4	Z = 2
Mr = 338.39	F(000) = 360
Triclinic, P1	Dx = 1.231 Mg m−3
a = 6.9790 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.9975 (8) Å	Cell parameters from 1203 reflections
c = 13.8202 (11) Å	θ = 2.8–25.6°
α = 77.899 (1)°	µ = 0.08 mm−1
β = 78.956 (2)°	T = 298 K
γ = 78.507 (2)°	Lump, colorless
V = 912.58 (11) Å3	0.35 × 0.32 × 0.31 mm

Bruker SMART APEX diffractometer	1735 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.024
Graphite monochromator	θmax = 25.0°, θmin = 3.0°
ω scans	h = −8→8
4547 measured reflections	k = −11→11
3138 independent reflections	l = −16→12

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.152	H-atom parameters constrained
S = 1.06	w = 1/[σ2(Fo2) + (0.057P)2 + 0.0883P] where P = (Fo2 + 2Fc2)/3
3138 reflections	(Δ/σ)max = 0.001
229 parameters	Δρmax = 0.15 e Å−3
0 restraints	Δρmin = −0.18 e Å−3

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

	x	y	z	Uiso*/Ueq
O1	0.8842 (3)	0.47521 (18)	0.39744 (12)	0.0647 (5)
H1	0.9635	0.5150	0.4123	0.097*
O2	0.8460 (3)	0.39954 (17)	0.56073 (13)	0.0578 (5)
O3	0.6238 (3)	0.21943 (17)	0.64005 (12)	0.0622 (5)
H3	0.7100	0.2662	0.6362	0.093*
O4	0.1871 (3)	0.12244 (19)	0.45984 (13)	0.0699 (6)
C1	0.7933 (3)	0.4066 (2)	0.47912 (19)	0.0460 (6)
C2	0.6332 (3)	0.3384 (2)	0.46785 (17)	0.0425 (6)
C3	0.5566 (3)	0.2451 (2)	0.55136 (17)	0.0460 (6)
C4	0.4102 (3)	0.1710 (2)	0.54695 (18)	0.0474 (6)
C5	0.3353 (4)	0.1946 (3)	0.45837 (19)	0.0508 (7)
C6	0.4050 (4)	0.2864 (2)	0.37512 (18)	0.0500 (6)
H6	0.3517	0.2992	0.3165	0.060*
C7	0.5533 (3)	0.3596 (2)	0.37766 (17)	0.0442 (6)
C8	0.3312 (4)	0.0732 (3)	0.63820 (18)	0.0568 (7)
H8A	0.2964	−0.0038	0.6164	0.068*
H8B	0.4356	0.0358	0.6786	0.068*
C9	0.1559 (4)	0.1381 (3)	0.7015 (2)	0.0639 (8)
H9	0.0923	0.2237	0.6723	0.077*
C10	0.0802 (5)	0.0907 (3)	0.7923 (2)	0.0786 (9)
C11	0.1714 (8)	−0.0452 (5)	0.8471 (3)	0.170 (2)
H11A	0.1457	−0.1193	0.8198	0.255*
H11B	0.1155	−0.0549	0.9168	0.255*
H11C	0.3118	−0.0485	0.8400	0.255*
C12	−0.0985 (6)	0.1646 (4)	0.8487 (3)	0.1287 (15)
H12A	−0.1369	0.2547	0.8104	0.193*
H12B	−0.0693	0.1745	0.9117	0.193*
H12C	−0.2048	0.1124	0.8603	0.193*
C13	0.6113 (4)	0.4597 (3)	0.28730 (18)	0.0516 (7)
H13	0.6350	0.5444	0.2960	0.062*
C14	0.6320 (4)	0.4374 (3)	0.1946 (2)	0.0628 (8)
H14	0.6173	0.3498	0.1874	0.075*
C15	0.6759 (4)	0.5363 (4)	0.1019 (2)	0.0683 (8)
C16	0.6483 (5)	0.6766 (4)	0.1000 (2)	0.0940 (11)
H16	0.6044	0.7111	0.1593	0.113*
C17	0.6849 (7)	0.7665 (5)	0.0111 (3)	0.1376 (17)
H17	0.6664	0.8613	0.0107	0.165*
C18	0.7484 (8)	0.7173 (7)	−0.0768 (4)	0.139 (2)
H18	0.7703	0.7791	−0.1367	0.167*
C19	0.7796 (6)	0.5793 (7)	−0.0771 (3)	0.1203 (17)
H19	0.8273	0.5457	−0.1366	0.144*
C20	0.7398 (5)	0.4888 (4)	0.0121 (2)	0.0903 (11)
H20	0.7564	0.3943	0.0116	0.108*
C21	0.1162 (4)	0.1248 (3)	0.3689 (2)	0.0719 (8)
H21A	0.0509	0.2167	0.3455	0.108*
H21B	0.0245	0.0610	0.3810	0.108*
H21C	0.2257	0.0983	0.3191	0.108*

	U11	U22	U33	U12	U13	U23
O1	0.0679 (12)	0.0791 (13)	0.0572 (11)	−0.0449 (10)	−0.0144 (9)	0.0008 (10)
O2	0.0604 (12)	0.0644 (12)	0.0567 (11)	−0.0276 (9)	−0.0195 (9)	−0.0032 (9)
O3	0.0674 (12)	0.0704 (12)	0.0540 (11)	−0.0300 (10)	−0.0169 (9)	0.0021 (9)
O4	0.0663 (13)	0.0852 (14)	0.0689 (13)	−0.0438 (11)	−0.0076 (10)	−0.0106 (10)
C1	0.0412 (15)	0.0437 (15)	0.0537 (16)	−0.0126 (12)	−0.0063 (13)	−0.0060 (12)
C2	0.0386 (14)	0.0433 (14)	0.0484 (14)	−0.0123 (11)	−0.0041 (11)	−0.0114 (11)
C3	0.0459 (15)	0.0477 (15)	0.0452 (14)	−0.0110 (12)	−0.0071 (12)	−0.0068 (12)
C4	0.0431 (15)	0.0463 (15)	0.0539 (15)	−0.0160 (12)	−0.0011 (12)	−0.0089 (12)
C5	0.0436 (15)	0.0542 (16)	0.0600 (16)	−0.0195 (13)	−0.0015 (13)	−0.0171 (13)
C6	0.0474 (15)	0.0564 (16)	0.0513 (15)	−0.0165 (13)	−0.0098 (12)	−0.0119 (13)
C7	0.0400 (14)	0.0453 (14)	0.0491 (14)	−0.0129 (11)	−0.0039 (11)	−0.0103 (12)
C8	0.0527 (17)	0.0517 (16)	0.0648 (17)	−0.0180 (13)	−0.0067 (14)	−0.0014 (13)
C9	0.0547 (18)	0.0699 (19)	0.0581 (18)	−0.0097 (15)	−0.0068 (14)	0.0062 (15)
C10	0.085 (2)	0.092 (2)	0.0524 (18)	−0.0209 (19)	−0.0035 (17)	0.0007 (17)
C11	0.214 (5)	0.129 (4)	0.099 (3)	0.012 (4)	0.032 (3)	0.041 (3)
C12	0.112 (3)	0.169 (4)	0.081 (3)	−0.009 (3)	0.022 (2)	−0.016 (3)
C13	0.0487 (16)	0.0574 (16)	0.0534 (16)	−0.0189 (13)	−0.0129 (12)	−0.0063 (13)
C14	0.0596 (18)	0.075 (2)	0.0587 (18)	−0.0266 (15)	−0.0070 (14)	−0.0099 (15)
C15	0.0539 (18)	0.102 (3)	0.0540 (18)	−0.0332 (17)	−0.0130 (14)	−0.0010 (17)
C16	0.110 (3)	0.101 (3)	0.068 (2)	−0.039 (2)	−0.0156 (19)	0.015 (2)
C17	0.161 (4)	0.140 (4)	0.099 (3)	−0.062 (3)	−0.025 (3)	0.045 (3)
C18	0.124 (4)	0.208 (6)	0.077 (3)	−0.080 (4)	−0.030 (3)	0.055 (4)
C19	0.085 (3)	0.221 (5)	0.055 (2)	−0.051 (4)	−0.0123 (19)	0.001 (3)
C20	0.075 (2)	0.145 (3)	0.056 (2)	−0.038 (2)	−0.0091 (16)	−0.014 (2)
C21	0.0644 (19)	0.083 (2)	0.085 (2)	−0.0313 (16)	−0.0194 (16)	−0.0250 (17)

O1—C1	1.312 (3)	C11—H11A	0.9600
O1—H1	0.8200	C11—H11B	0.9600
O2—C1	1.236 (3)	C11—H11C	0.9600
O3—C3	1.352 (3)	C12—H12A	0.9600
O3—H3	0.8200	C12—H12B	0.9600
O4—C5	1.368 (3)	C12—H12C	0.9600
O4—C21	1.430 (3)	C13—C14	1.322 (3)
C1—C2	1.467 (3)	C13—H13	0.9300
C2—C3	1.414 (3)	C14—C15	1.467 (4)
C2—C7	1.420 (3)	C14—H14	0.9300
C3—C4	1.393 (3)	C15—C16	1.372 (4)
C4—C5	1.379 (3)	C15—C20	1.384 (4)
C4—C8	1.511 (3)	C16—C17	1.375 (4)
C5—C6	1.387 (3)	C16—H16	0.9300
C6—C7	1.391 (3)	C17—C18	1.367 (6)
C6—H6	0.9300	C17—H17	0.9300
C7—C13	1.472 (3)	C18—C19	1.354 (6)
C8—C9	1.482 (4)	C18—H18	0.9300
C8—H8A	0.9700	C19—C20	1.384 (5)
C8—H8B	0.9700	C19—H19	0.9300
C9—C10	1.294 (4)	C20—H20	0.9300
C9—H9	0.9300	C21—H21A	0.9600
C10—C12	1.487 (4)	C21—H21B	0.9600
C10—C11	1.494 (5)	C21—H21C	0.9600
C1—O1—H1	109.5	C10—C11—H11C	109.5
C3—O3—H3	109.5	H11A—C11—H11C	109.5
C5—O4—C21	119.8 (2)	H11B—C11—H11C	109.5
O2—C1—O1	120.0 (2)	C10—C12—H12A	109.5
O2—C1—C2	122.9 (2)	C10—C12—H12B	109.5
O1—C1—C2	117.1 (2)	H12A—C12—H12B	109.5
C3—C2—C7	118.5 (2)	C10—C12—H12C	109.5
C3—C2—C1	117.8 (2)	H12A—C12—H12C	109.5
C7—C2—C1	123.7 (2)	H12B—C12—H12C	109.5
O3—C3—C4	115.6 (2)	C14—C13—C7	124.5 (2)
O3—C3—C2	122.2 (2)	C14—C13—H13	117.8
C4—C3—C2	122.2 (2)	C7—C13—H13	117.8
C5—C4—C3	117.8 (2)	C13—C14—C15	126.9 (3)
C5—C4—C8	121.7 (2)	C13—C14—H14	116.6
C3—C4—C8	120.5 (2)	C15—C14—H14	116.6
O4—C5—C4	115.0 (2)	C16—C15—C20	118.1 (3)
O4—C5—C6	123.2 (2)	C16—C15—C14	122.2 (3)
C4—C5—C6	121.7 (2)	C20—C15—C14	119.6 (3)
C5—C6—C7	121.3 (2)	C15—C16—C17	120.5 (4)
C5—C6—H6	119.4	C15—C16—H16	119.7
C7—C6—H6	119.4	C17—C16—H16	119.7
C6—C7—C2	118.5 (2)	C18—C17—C16	120.4 (5)
C6—C7—C13	117.4 (2)	C18—C17—H17	119.8
C2—C7—C13	124.0 (2)	C16—C17—H17	119.8
C9—C8—C4	114.1 (2)	C19—C18—C17	120.4 (4)
C9—C8—H8A	108.7	C19—C18—H18	119.8
C4—C8—H8A	108.7	C17—C18—H18	119.8
C9—C8—H8B	108.7	C18—C19—C20	119.2 (4)
C4—C8—H8B	108.7	C18—C19—H19	120.4
H8A—C8—H8B	107.6	C20—C19—H19	120.4
C10—C9—C8	128.2 (3)	C19—C20—C15	121.3 (4)
C10—C9—H9	115.9	C19—C20—H20	119.4
C8—C9—H9	115.9	C15—C20—H20	119.4
C9—C10—C12	123.6 (3)	O4—C21—H21A	109.5
C9—C10—C11	120.6 (3)	O4—C21—H21B	109.5
C12—C10—C11	115.8 (3)	H21A—C21—H21B	109.5
C10—C11—H11A	109.5	O4—C21—H21C	109.5
C10—C11—H11B	109.5	H21A—C21—H21C	109.5
H11A—C11—H11B	109.5	H21B—C21—H21C	109.5
O2—C1—C2—C3	−9.3 (3)	C3—C2—C7—C6	−0.8 (3)
O1—C1—C2—C3	169.4 (2)	C1—C2—C7—C6	178.3 (2)
O2—C1—C2—C7	171.6 (2)	C3—C2—C7—C13	176.3 (2)
O1—C1—C2—C7	−9.7 (3)	C1—C2—C7—C13	−4.6 (4)
C7—C2—C3—O3	−179.7 (2)	C5—C4—C8—C9	−86.0 (3)
C1—C2—C3—O3	1.1 (3)	C3—C4—C8—C9	91.3 (3)
C7—C2—C3—C4	1.8 (3)	C4—C8—C9—C10	−165.1 (3)
C1—C2—C3—C4	−177.4 (2)	C8—C9—C10—C12	−179.4 (3)
O3—C3—C4—C5	179.4 (2)	C8—C9—C10—C11	0.7 (6)
C2—C3—C4—C5	−2.1 (3)	C6—C7—C13—C14	−41.1 (3)
O3—C3—C4—C8	1.9 (3)	C2—C7—C13—C14	141.8 (3)
C2—C3—C4—C8	−179.5 (2)	C7—C13—C14—C15	175.4 (2)
C21—O4—C5—C4	−171.9 (2)	C13—C14—C15—C16	−18.2 (5)
C21—O4—C5—C6	8.9 (4)	C13—C14—C15—C20	164.4 (3)
C3—C4—C5—O4	−177.8 (2)	C20—C15—C16—C17	−0.5 (5)
C8—C4—C5—O4	−0.4 (3)	C14—C15—C16—C17	−177.9 (3)
C3—C4—C5—C6	1.4 (4)	C15—C16—C17—C18	0.4 (6)
C8—C4—C5—C6	178.8 (2)	C16—C17—C18—C19	−1.3 (8)
O4—C5—C6—C7	178.7 (2)	C17—C18—C19—C20	2.3 (7)
C4—C5—C6—C7	−0.4 (4)	C18—C19—C20—C15	−2.4 (6)
C5—C6—C7—C2	0.1 (3)	C16—C15—C20—C19	1.5 (5)
C5—C6—C7—C13	−177.2 (2)	C14—C15—C20—C19	179.0 (3)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2i	0.82	1.85	2.667 (2)	176
O3—H3···O2	0.82	1.82	2.546 (2)	147

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O2i	0.82	1.85	2.667 (2)	176
O3—H3⋯O2	0.82	1.82	2.546 (2)	147

Symmetry code: (i) .