rac-Ethyl 2-hy-droxy-2,7,7-trimethyl-4-(4-nitro-phen-yl)-5-oxo-3,4,5,6,7,8-hexa-hydro-2H-chromene-3-carboxyl-ate.

The title mol-ecule, C21H25NO7, has four stereogenic centres and crystallized as a racemate. It consists of enanti-omeric pairs with the relative configuration rac-(1R*,2S*,3R*). The cyclo-hexenone ring adopts an envelope conformation; the dimethyl-substituted C atom lies 0.640 (1) Å out of the mean plane formed by the rest of the ring atoms (r.m.s. deviation = 0.016 Å). The oxacyclo-hexene ring adopts a half-chair conformation, the hy-droxy- and carboxyl-substituted C atoms lying -0.336 (1) and 0.419 (1) Å, respectively, out of the mean plane formed by the rest of the ring atoms (r.m.s. deviation = 0.002 Å). In the crystal, O-H⋯O hydrogen bonds link the mol-ecules into a chain along the c-axis direction.

Related literature

For general background to 2H-chromenes and their derivatives, see: Cai (2008 ▶); Valenti et al. (1993 ▶); Hyana & Saimoto (1987 ▶); Tang et al. (2007 ▶). For their anti­cancer activity, see: Afanti­tis et al. (2006 ▶); Cai (2007 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶).

Experimental

Crystal data

C21H25NO7

M = 403.42

Monoclinic,

a = 10.4163 (8) Å

b = 24.2608 (18) Å

c = 8.0796 (6) Å

β = 96.437 (2)°

V = 2028.9 (3) Å3

Z = 4

Mo Kα radiation

μ = 0.10 mm−1

T = 296 K

0.30 × 0.20 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 1998 ▶) T min = 0.971, T max = 0.980

23423 measured reflections

5078 independent reflections

4084 reflections with I > 2σ(I)

R int = 0.022

Refinement

R[F 2 > 2σ(F 2)] = 0.044

wR(F 2) = 0.118

S = 1.00

5078 reflections

266 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.30 e Å−3

Δρmin = −0.20 e Å−3

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus (Bruker, 2005 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Click here for additional data file.

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812050581/aa2078sup1.cif

Click here for additional data file.

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812050581/aa2078Isup2.hkl

Click here for additional data file.

Supplementary material file. DOI: 10.1107/S1600536812050581/aa2078Isup3.cml

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

C21H25NO7	F(000) = 856
Mr = 403.42	Dx = 1.321 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6760 reflections
a = 10.4163 (8) Å	θ = 2.7–28.5°
b = 24.2608 (18) Å	µ = 0.10 mm−1
c = 8.0796 (6) Å	T = 296 K
β = 96.437 (2)°	Prism, yellow
V = 2028.9 (3) Å3	0.30 × 0.20 × 0.20 mm
Z = 4

Bruker APEXII CCD diffractometer	5078 independent reflections
Radiation source: fine-focus sealed tube	4084 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
φ and ω scans	θmax = 28.4°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1998)	h = −13→13
Tmin = 0.971, Tmax = 0.980	k = −32→32
23423 measured reflections	l = −10→10

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)] = 0.044	Hydrogen site location: difference Fourier map
wR(F2) = 0.118	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ2(Fo2) + (0.0521P)2 + 0.7463P] where P = (Fo2 + 2Fc2)/3
5078 reflections	(Δ/σ)max = 0.001
266 parameters	Δρmax = 0.30 e Å−3
0 restraints	Δρmin = −0.20 e Å−3

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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	0.06693 (9)	0.68270 (4)	0.29152 (11)	0.0360 (2)
O2	−0.04636 (10)	0.74080 (4)	0.10075 (13)	0.0383 (2)
H2	−0.080 (2)	0.7620 (9)	0.162 (3)	0.061 (6)*
O3	−0.17047 (10)	0.67735 (4)	−0.21204 (13)	0.0427 (3)
O4	−0.23488 (9)	0.60735 (4)	−0.06145 (12)	0.0366 (2)
O5	0.23965 (18)	0.44094 (6)	−0.4474 (2)	0.0829 (5)
O6	0.16430 (16)	0.49162 (6)	−0.65423 (17)	0.0721 (4)
O7	0.35300 (11)	0.66576 (5)	−0.11760 (13)	0.0508 (3)
N1	0.18908 (15)	0.48317 (6)	−0.5053 (2)	0.0522 (4)
C1	−0.04561 (12)	0.68823 (6)	0.16883 (16)	0.0314 (3)
C2	−0.03255 (12)	0.64615 (5)	0.03021 (15)	0.0297 (3)
H2A	−0.0244	0.6095	0.0812	0.036*
C3	0.08949 (12)	0.65704 (5)	−0.05552 (16)	0.0303 (3)
H3A	0.0758	0.6908	−0.1218	0.036*
C4	0.20193 (13)	0.66649 (6)	0.07676 (16)	0.0322 (3)
C5	0.33285 (14)	0.66857 (6)	0.02822 (18)	0.0370 (3)
C6	0.44363 (14)	0.67805 (8)	0.1622 (2)	0.0467 (4)
H6A	0.4666	0.7168	0.1616	0.056*
H6B	0.5176	0.6573	0.1335	0.056*
C7	0.41940 (14)	0.66238 (7)	0.33864 (19)	0.0411 (3)
C8	0.29096 (13)	0.68842 (7)	0.37109 (18)	0.0393 (3)
H8A	0.2660	0.6740	0.4748	0.047*
H8B	0.3028	0.7279	0.3842	0.047*
C9	0.18422 (12)	0.67797 (5)	0.23553 (17)	0.0323 (3)
C10	−0.15932 (14)	0.67843 (7)	0.26566 (19)	0.0432 (3)
H10A	−0.1609	0.7063	0.3498	0.065*
H10B	−0.1514	0.6428	0.3174	0.065*
H10C	−0.2379	0.6800	0.1914	0.065*
C11	−0.15205 (12)	0.64616 (5)	−0.09602 (16)	0.0310 (3)
C12	−0.35486 (14)	0.60395 (7)	−0.17297 (19)	0.0407 (3)
H12A	−0.3363	0.6005	−0.2875	0.049*
H12B	−0.4062	0.6369	−0.1634	0.049*
C13	−0.42646 (19)	0.55435 (8)	−0.1231 (3)	0.0638 (5)
H13A	−0.5062	0.5509	−0.1944	0.096*
H13B	−0.4443	0.5583	−0.0097	0.096*
H13C	−0.3748	0.5220	−0.1333	0.096*
C14	0.11142 (13)	0.60989 (6)	−0.17235 (16)	0.0325 (3)
C15	0.08635 (14)	0.61724 (6)	−0.34299 (17)	0.0371 (3)
H15A	0.0540	0.6508	−0.3847	0.044*
C16	0.10879 (15)	0.57534 (6)	−0.45185 (18)	0.0410 (3)
H16A	0.0915	0.5804	−0.5663	0.049*
C17	0.15694 (14)	0.52615 (6)	−0.38837 (19)	0.0396 (3)
C18	0.17904 (16)	0.51659 (6)	−0.2196 (2)	0.0456 (4)
H18A	0.2094	0.4826	−0.1788	0.055*
C19	0.15505 (16)	0.55868 (6)	−0.11237 (18)	0.0428 (3)
H19A	0.1683	0.5527	0.0020	0.051*
C20	0.41427 (19)	0.59983 (8)	0.3586 (3)	0.0623 (5)
H20A	0.4956	0.5841	0.3380	0.093*
H20B	0.3467	0.5850	0.2806	0.093*
H20C	0.3973	0.5910	0.4699	0.093*
C21	0.52760 (16)	0.68578 (9)	0.4625 (2)	0.0565 (5)
H21A	0.6084	0.6694	0.4427	0.085*
H21B	0.5101	0.6776	0.5740	0.085*
H21C	0.5322	0.7250	0.4485	0.085*

	U11	U22	U33	U12	U13	U23
O1	0.0287 (5)	0.0509 (6)	0.0282 (4)	0.0038 (4)	0.0028 (4)	−0.0004 (4)
O2	0.0428 (6)	0.0338 (5)	0.0386 (5)	0.0051 (4)	0.0056 (4)	−0.0010 (4)
O3	0.0407 (6)	0.0451 (6)	0.0406 (5)	−0.0048 (4)	−0.0030 (4)	0.0116 (4)
O4	0.0338 (5)	0.0386 (5)	0.0367 (5)	−0.0063 (4)	−0.0001 (4)	0.0030 (4)
O5	0.1139 (14)	0.0500 (8)	0.0884 (11)	0.0253 (8)	0.0266 (10)	−0.0098 (7)
O6	0.0927 (11)	0.0727 (9)	0.0532 (8)	0.0037 (8)	0.0182 (7)	−0.0222 (7)
O7	0.0390 (6)	0.0750 (8)	0.0403 (6)	0.0008 (5)	0.0130 (5)	−0.0018 (5)
N1	0.0546 (8)	0.0424 (8)	0.0626 (9)	−0.0018 (6)	0.0190 (7)	−0.0137 (7)
C1	0.0268 (6)	0.0373 (7)	0.0303 (6)	0.0010 (5)	0.0037 (5)	0.0006 (5)
C2	0.0287 (6)	0.0310 (6)	0.0296 (6)	0.0016 (5)	0.0035 (5)	0.0019 (5)
C3	0.0291 (6)	0.0326 (6)	0.0293 (6)	0.0035 (5)	0.0043 (5)	0.0014 (5)
C4	0.0277 (6)	0.0348 (7)	0.0341 (6)	0.0019 (5)	0.0036 (5)	0.0006 (5)
C5	0.0322 (7)	0.0394 (7)	0.0399 (7)	0.0011 (5)	0.0065 (6)	0.0009 (6)
C6	0.0292 (7)	0.0652 (10)	0.0461 (8)	−0.0052 (7)	0.0053 (6)	−0.0018 (7)
C7	0.0297 (7)	0.0498 (9)	0.0429 (8)	0.0030 (6)	0.0002 (6)	0.0019 (6)
C8	0.0324 (7)	0.0495 (8)	0.0349 (7)	0.0022 (6)	−0.0005 (5)	−0.0021 (6)
C9	0.0277 (6)	0.0341 (7)	0.0348 (7)	0.0029 (5)	0.0027 (5)	0.0024 (5)
C10	0.0341 (7)	0.0583 (9)	0.0389 (8)	−0.0044 (6)	0.0111 (6)	−0.0066 (7)
C11	0.0301 (6)	0.0311 (6)	0.0322 (6)	0.0009 (5)	0.0050 (5)	−0.0018 (5)
C12	0.0315 (7)	0.0476 (8)	0.0418 (7)	−0.0025 (6)	−0.0008 (6)	−0.0028 (6)
C13	0.0486 (10)	0.0582 (11)	0.0821 (13)	−0.0178 (8)	−0.0033 (9)	0.0004 (10)
C14	0.0294 (6)	0.0362 (7)	0.0321 (6)	0.0027 (5)	0.0047 (5)	−0.0005 (5)
C15	0.0412 (7)	0.0371 (7)	0.0336 (7)	0.0074 (6)	0.0073 (6)	0.0021 (5)
C16	0.0461 (8)	0.0454 (8)	0.0324 (7)	0.0014 (6)	0.0087 (6)	−0.0019 (6)
C17	0.0379 (7)	0.0371 (7)	0.0453 (8)	−0.0003 (6)	0.0112 (6)	−0.0077 (6)
C18	0.0509 (9)	0.0348 (7)	0.0509 (9)	0.0091 (6)	0.0041 (7)	0.0015 (6)
C19	0.0517 (9)	0.0407 (8)	0.0349 (7)	0.0074 (7)	0.0001 (6)	0.0028 (6)
C20	0.0519 (10)	0.0541 (11)	0.0790 (13)	0.0110 (8)	−0.0003 (9)	0.0108 (9)
C21	0.0344 (8)	0.0817 (13)	0.0508 (9)	0.0015 (8)	−0.0066 (7)	−0.0023 (9)

O1—C9	1.3544 (16)	C8—C9	1.4924 (18)
O1—C1	1.4541 (15)	C8—H8A	0.9700
O2—C1	1.3885 (17)	C8—H8B	0.9700
O2—H2	0.82 (2)	C10—H10A	0.9600
O3—C11	1.2032 (16)	C10—H10B	0.9600
O4—C11	1.3278 (16)	C10—H10C	0.9600
O4—C12	1.4588 (17)	C12—C13	1.494 (2)
O5—N1	1.221 (2)	C12—H12A	0.9700
O6—N1	1.219 (2)	C12—H12B	0.9700
O7—C5	1.2216 (17)	C13—H13A	0.9600
N1—C17	1.4706 (19)	C13—H13B	0.9600
C1—C10	1.5096 (19)	C13—H13C	0.9600
C1—C2	1.5328 (18)	C14—C15	1.3857 (19)
C2—C11	1.5182 (18)	C14—C19	1.391 (2)
C2—C3	1.5373 (18)	C15—C16	1.381 (2)
C2—H2A	0.9800	C15—H15A	0.9300
C3—C4	1.5119 (18)	C16—C17	1.372 (2)
C3—C14	1.5166 (18)	C16—H16A	0.9300
C3—H3A	0.9800	C17—C18	1.377 (2)
C4—C9	1.3454 (19)	C18—C19	1.380 (2)
C4—C5	1.4615 (19)	C18—H18A	0.9300
C5—C6	1.509 (2)	C19—H19A	0.9300
C6—C7	1.524 (2)	C20—H20A	0.9600
C6—H6A	0.9700	C20—H20B	0.9600
C6—H6B	0.9700	C20—H20C	0.9600
C7—C20	1.528 (2)	C21—H21A	0.9600
C7—C8	1.529 (2)	C21—H21B	0.9600
C7—C21	1.530 (2)	C21—H21C	0.9600
C9—O1—C1	117.94 (10)	C1—C10—H10A	109.5
C1—O2—H2	108.7 (15)	C1—C10—H10B	109.5
C11—O4—C12	116.24 (11)	H10A—C10—H10B	109.5
O6—N1—O5	123.61 (15)	C1—C10—H10C	109.5
O6—N1—C17	118.46 (15)	H10A—C10—H10C	109.5
O5—N1—C17	117.93 (15)	H10B—C10—H10C	109.5
O2—C1—O1	108.85 (11)	O3—C11—O4	124.00 (12)
O2—C1—C10	112.34 (12)	O3—C11—C2	124.80 (12)
O1—C1—C10	104.57 (11)	O4—C11—C2	111.20 (11)
O2—C1—C2	108.62 (10)	O4—C12—C13	107.34 (13)
O1—C1—C2	107.81 (10)	O4—C12—H12A	110.2
C10—C1—C2	114.38 (11)	C13—C12—H12A	110.2
C11—C2—C1	110.94 (10)	O4—C12—H12B	110.2
C11—C2—C3	110.76 (10)	C13—C12—H12B	110.2
C1—C2—C3	111.12 (11)	H12A—C12—H12B	108.5
C11—C2—H2A	108.0	C12—C13—H13A	109.5
C1—C2—H2A	108.0	C12—C13—H13B	109.5
C3—C2—H2A	108.0	H13A—C13—H13B	109.5
C4—C3—C14	113.29 (11)	C12—C13—H13C	109.5
C4—C3—C2	108.77 (10)	H13A—C13—H13C	109.5
C14—C3—C2	109.91 (11)	H13B—C13—H13C	109.5
C4—C3—H3A	108.2	C15—C14—C19	118.63 (13)
C14—C3—H3A	108.2	C15—C14—C3	119.84 (12)
C2—C3—H3A	108.2	C19—C14—C3	121.53 (12)
C9—C4—C5	118.72 (12)	C16—C15—C14	120.83 (13)
C9—C4—C3	121.82 (12)	C16—C15—H15A	119.6
C5—C4—C3	119.19 (12)	C14—C15—H15A	119.6
O7—C5—C4	121.55 (13)	C17—C16—C15	118.89 (13)
O7—C5—C6	120.01 (13)	C17—C16—H16A	120.6
C4—C5—C6	118.32 (12)	C15—C16—H16A	120.6
C5—C6—C7	116.08 (13)	C16—C17—C18	122.03 (13)
C5—C6—H6A	108.3	C16—C17—N1	118.47 (14)
C7—C6—H6A	108.3	C18—C17—N1	119.48 (14)
C5—C6—H6B	108.3	C17—C18—C19	118.37 (14)
C7—C6—H6B	108.3	C17—C18—H18A	120.8
H6A—C6—H6B	107.4	C19—C18—H18A	120.8
C6—C7—C20	111.00 (15)	C18—C19—C14	121.16 (14)
C6—C7—C8	107.29 (12)	C18—C19—H19A	119.4
C20—C7—C8	110.53 (14)	C14—C19—H19A	119.4
C6—C7—C21	109.40 (14)	C7—C20—H20A	109.5
C20—C7—C21	109.35 (14)	C7—C20—H20B	109.5
C8—C7—C21	109.22 (13)	H20A—C20—H20B	109.5
C9—C8—C7	113.47 (12)	C7—C20—H20C	109.5
C9—C8—H8A	108.9	H20A—C20—H20C	109.5
C7—C8—H8A	108.9	H20B—C20—H20C	109.5
C9—C8—H8B	108.9	C7—C21—H21A	109.5
C7—C8—H8B	108.9	C7—C21—H21B	109.5
H8A—C8—H8B	107.7	H21A—C21—H21B	109.5
C4—C9—O1	124.14 (12)	C7—C21—H21C	109.5
C4—C9—C8	124.36 (12)	H21A—C21—H21C	109.5
O1—C9—C8	111.48 (11)	H21B—C21—H21C	109.5
C9—O1—C1—O2	−73.27 (14)	C5—C4—C9—C8	−5.2 (2)
C9—O1—C1—C10	166.48 (12)	C3—C4—C9—C8	−179.15 (13)
C9—O1—C1—C2	44.38 (15)	C1—O1—C9—C4	−14.56 (19)
O2—C1—C2—C11	−66.83 (13)	C1—O1—C9—C8	164.06 (11)
O1—C1—C2—C11	175.37 (10)	C7—C8—C9—C4	−24.3 (2)
C10—C1—C2—C11	59.55 (15)	C7—C8—C9—O1	157.08 (12)
O2—C1—C2—C3	56.85 (13)	C12—O4—C11—O3	−0.54 (19)
O1—C1—C2—C3	−60.94 (13)	C12—O4—C11—C2	179.02 (11)
C10—C1—C2—C3	−176.77 (11)	C1—C2—C11—O3	84.53 (16)
C11—C2—C3—C4	170.27 (11)	C3—C2—C11—O3	−39.36 (18)
C1—C2—C3—C4	46.48 (14)	C1—C2—C11—O4	−95.03 (13)
C11—C2—C3—C14	−65.16 (13)	C3—C2—C11—O4	141.08 (11)
C1—C2—C3—C14	171.05 (10)	C11—O4—C12—C13	174.00 (14)
C14—C3—C4—C9	−138.81 (13)	C4—C3—C14—C15	−131.87 (13)
C2—C3—C4—C9	−16.27 (17)	C2—C3—C14—C15	106.22 (14)
C14—C3—C4—C5	47.28 (17)	C4—C3—C14—C19	48.91 (18)
C2—C3—C4—C5	169.83 (12)	C2—C3—C14—C19	−73.00 (16)
C9—C4—C5—O7	−170.20 (14)	C19—C14—C15—C16	−2.4 (2)
C3—C4—C5—O7	3.9 (2)	C3—C14—C15—C16	178.31 (13)
C9—C4—C5—C6	5.9 (2)	C14—C15—C16—C17	−0.2 (2)
C3—C4—C5—C6	179.98 (13)	C15—C16—C17—C18	2.5 (2)
O7—C5—C6—C7	−160.47 (15)	C15—C16—C17—N1	−175.77 (14)
C4—C5—C6—C7	23.4 (2)	O6—N1—C17—C16	−4.4 (2)
C5—C6—C7—C20	71.49 (18)	O5—N1—C17—C16	175.33 (16)
C5—C6—C7—C8	−49.37 (19)	O6—N1—C17—C18	177.29 (16)
C5—C6—C7—C21	−167.74 (15)	O5—N1—C17—C18	−2.9 (2)
C6—C7—C8—C9	48.98 (17)	C16—C17—C18—C19	−1.9 (2)
C20—C7—C8—C9	−72.17 (17)	N1—C17—C18—C19	176.34 (14)
C21—C7—C8—C9	167.47 (14)	C17—C18—C19—C14	−0.9 (2)
C5—C4—C9—O1	173.22 (13)	C15—C14—C19—C18	3.1 (2)
C3—C4—C9—O1	−0.7 (2)	C3—C14—C19—C18	−177.72 (14)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O3i	0.82 (2)	2.08 (2)	2.8881 (15)	172 (2)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O3i	0.82 (2)	2.08 (2)	2.8881 (15)	172 (2)

Symmetry code: (i) .