5,5-Di­methoxy-2-phenoxy-1,3,2-dioxaphosphorinane 2-oxide

In the title compound, C₁₁H₁₅O₆P, the six-membered dioxa­phospho­rinane ring of the cyclic phosphate triester exists in a distorted chair conformation, with the phenoxy group in an axial position. The phenyl ring and both methoxy groups are in a trans–gauche orientation with respect to the 1,3,2-di­oxa­phospho­rinane ring. In the phosphate group, a significant deformation from the ideal tetrahedral shape is observed. The crystal structure is stabilized by a three-dimensional network of C—H...O interactions.

S1. Comment

The title compound, (4), the phenyl ester of cyclic dihydroxyacetone phosphate dimethyl acetal, is one of the intermediates on the chemical pathway leading from dihydroxyacetone (DHA) to dihydroxyacetone phosphate (DHAP) described by Ferroni et al. (1999). The present paper is the second of a series of crystal structure investigations of this chemical pathway, which we have undertaken as a completion of our research on DHAP, its precursors and analogues (Mazurek & Lis, 1999; Ślepokura et al., 2003). The other compounds, namely DHA in the monomeric and three dimeric forms, and two complexes of DHA with calcium chloride and dihydroxyacetone dimethyl acetal, are reported elsewhere (Ślepokura & Lis, 2004). In general, six-membered cyclic phosphate esters are constituents present in a number of biologically important molecules, e.g. cyclic adenosine monophosphate.

The molecular structure and atom-numbering scheme of (4) are shown in Fig. 1. In one of the methyl groups (C52), the H atoms are disordered over two sites. Excellent agreement is observed between the geometric features of the six-membered ring (O1/P2/O3/C4–C6) of the title compound and those of the structurally related 2-oxo-1,3,2-dioxaphosphorinanes and their derivatives (e.g. 2-hydroxy-5-methyl-5-nitro derivatives: Johnson et al., 1989; several 2-OAr derivatives: Jones et al., 1984; a 5-hydroxy-2-methoxy derivative: Hamor, 1986). The dioxaphosphorinane ring in (4) adopts a distorted chair conformation, with the phenoxyl group in an axial position. The dihedral angles between the least-squares plane through the four central atoms of the ring (O1, O3, C4 and C6) and the O1/P2/O3 and C4–C5–C6 planes are 35.86 (10) and 51.84 (15)°, respectively. The flattening of the ring at the P atom and the deformation of the chair conformation towards an envelope have been observed in similar cyclic structures (Jones et al., 1984). The seemingly energetically unfavourable location of the large phenoxy substituent in the axial position may be explained by the anomeric effect that has been noted previously in a cyclic phosphate (van Nuffel et al., 1980) and is commonly observed in structures such as that reported here. A similar location of the P-bonded substituents in the axial position was also observed in the case of alkyloxy groups, e.g. methoxy groups in methyl esters (Hamor, 1986) or in bicyclic organic pyro- and thiopyrophosphates, in which two cyclic thiophosphates are linked by an O atom (Bukowska-Strzyżewska & Dobrowolska, 1978; Bukowska-Strzyżewska & Dobrowolska, 1980; Jones et al., 1985). However, when the substituent is –NMe₂, its position is found to be equatorial (Cameron & Karolak-Wojciechowska, 1977, and references therein).

The orientation of the aromatic substituent with respect to the dioxaphosphorinane ring may be described as trans–gauche (tg), the C11—O22—P2—O1 and C11—O22—P2—O3 torsion angles being 176.70 (12) and 65.65 (13)°, respectively. Similarly, the location of both methoxy groups is found to be tg and gt with respect to the dioxaphosphorinane ring (Table 1).

In the phosphate group, a deformation from the ideal tetrahedral shape is observed, especially in the O1—P2—O22 and O21—P2—O22 bond angles. On the whole, the largest O—P—O angles (Table 1) are those associated with atom O21 of the P2=O21 double bond. Additionally, there are significant differences in the three ester P—O distances. The endocyclic P2—O1 distance is significantly shorter than the exocyclic P2—O22 distance. A similar situation was reported for the structures of five 2-oxo-2-aryloxy-1,3,2-dioxaphosphorinanes (Jones et al., 1984). As expected, the P2=O21 double bond is the shortest of the P—O bonds in (4).

The crystal structure of (4) is stabilized by a three-dimensional network of C—H···O intermolecular hydrogen bonds linking adjacent molecules (Table 2). As shown in Fig. 2, sheets of molecules are generated in the bc plane by means of C—H···O interactions linking the aromatic C14/H14 and methyl C51/H51C groups to adjacent O atoms of molecules related by the action of 2₁ screw axes; these interactions give rise to R⁴₄(30) rings. A direct a axis translation (Fig. 3) generates an infinite chain of molecules via C—H···O interactions linking the C4/H4A and C12/H12 groups with an adjacent O21 atom (Table 2), and the C52/H52A group with an adjacent ether atom (O51). In this way, R¹₂(9) and R²₂(12) rings are generated, and the sheets shown in Fig. 2 are linked into a three-dimensional network. One characteristic of the crystal packing in (4) (also shown in Fig. 2) is an alternate occurrence of aliphatic and aromatic layers parallel to (001), with the aromatic rings at z = 0, 1, 2 etc. and the aliphatic rings at z = 1/2, 1.5, etc.

S2. Experimental

Crystalline dimethyl acetal of cyclic dihydroxyacetone phosphate was obtained by phosphorylation of both hydroxy groups of dihydroxyacetone dimethyl acetal with PhOP(O)Cl₂ in anhydrous pyridine (Ferroni et al., 1999). Recrystallization of the crude product by slow evaporation of its benzene solution at room temperature gave large well formed colourless plates. NMR analysis (300 MHz, benzene–d₆, 297 K) reveals that the title compound also exists as a single conformer in solution at room temperature. ¹H NMR (p.p.m.): 7.30 (d, J_HH=8.4 Hz, 2H), 6.99 (t, J_HH=7.8 Hz, 2H), 6.83 (t, J_HH=7.4 Hz, 1H), 3.94–3.85 (m, 4H, CH₂ ring), 2.81 and 2.62 (2 s, 2 x 3H –OCH₃ ax, eq); ¹³C NMR (p.p.m.): 130.05, 125.14, 119.92 (d, J=5.1 Hz, CH), 93.20 (d, J_CCOP=6.1 Hz, C), 69.62 (d, J_COP=7.1 Hz, CH₂ ring), 48.53 and 48.46 (2 s, –OCH₃ ax, eq) (not all of the –Ph signals could be observed on the ¹³C NMR spectrum because of the large solvent signal); ³¹P NMR (p.p.m.): −12.91.

S3. Refinement

All H atoms were found in difference Fourier maps, which showed that the methyl H atoms on atom C52 were disordered equally over two sites. In the final refinement cycles, all H atoms were treated as riding atoms, with C—H ditances of 0.93–0.97 Å, and U_iso(H) values of 1.2U_eq(C) for aromatic and CH₂ H atoms and 1.5U_eq(C) for methyl H atoms.

Computing details

Data collection: KM-4 CCD Software (Oxford Diffraction, 1995–2003); cell refinement: KM-4 CCD Software; data reduction: KM-4 CCD Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003) and SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular structure and atom-numbering scheme of (4), showing the disorder of the H atoms at methyl atom C52. Displacement ellipsoids are drawn at the 40% probability level.
	Fig. 2. A view of the two-dimensional net of molecules in the bc plane. Atoms marked with an asterisk (*), dollar sign (), at sign (@) or hash (#) are at equivalent positions (1 − x,y − 1/2,1 − z), (1 − x,1/2 + y,1 − z), (1 − x,y − 1/2,2 − z) and (1 − x,1/2 + y,2 − z), respectively. Dashed lines indicate C—H···O contacts and H atoms not involved in these contacts are not shown.
	Fig. 3. A view showing the linking of molecules by a axis translation. Atoms marked with an asterisk (*) or a hash (#) are at equivalent positions (1 + x,y,z) and (−1 + x,y,z), respectively. Dashed lines indicate C—H···O contacts and H atoms not involved in these contacts are not shown.

5,5-dimethoxy-2-phenoxy-1,3,2-dioxaphosphorinan-2-one

Crystal data

C11H15O6P	F(000) = 288
Mr = 274.20	Dx = 1.483 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 6408 reflections
a = 6.024 (2) Å	θ = 3.8–37.4°
b = 10.371 (3) Å	µ = 0.24 mm^−1
c = 9.917 (3) Å	T = 100 K
β = 97.53 (3)°	Plates, colourless
V = 614.2 (3) Å^3	0.65 × 0.35 × 0.04 mm
Z = 2

Data collection

KUMA KM-4 CCD κ-geometry diffractometer	4232 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.041
Graphite monochromator	θmax = 37.4°, θmin = 3.8°
ω scans	h = −7→10
10758 measured reflections	k = −13→17
4632 independent reflections	l = −16→16

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.033	w = 1/[σ^2(Fo^2) + (0.0454P)^2 + 0.1259P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.082	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.27 e Å^−3
2908 reflections	Δρmin = −0.29 e Å^−3
166 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.015 (4)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.10 (8)

Special details

Experimental. The NMR measurements were performed with the use of a Bruker 300 MHz instrument.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
P2	0.51729 (6)	0.53328 (4)	0.66739 (4)	0.01414 (11)
O1	0.5564 (2)	0.40371 (12)	0.59181 (13)	0.0174 (3)
O3	0.5935 (2)	0.64523 (12)	0.57673 (13)	0.0159 (3)
O21	0.28971 (19)	0.55228 (14)	0.69860 (12)	0.0216 (3)
O22	0.70499 (17)	0.52286 (14)	0.79674 (11)	0.0166 (2)
O51	0.62017 (17)	0.51433 (12)	0.32757 (11)	0.0159 (3)
O52	1.0020 (2)	0.47564 (15)	0.39276 (13)	0.0238 (3)
C4	0.7970 (3)	0.63125 (18)	0.51241 (18)	0.0161 (3)
H4A	0.9272	0.6349	0.5812	0.019*
H4B	0.8073	0.7016	0.4491	0.019*
C5	0.7940 (3)	0.50255 (16)	0.43666 (17)	0.0157 (4)
C6	0.7632 (3)	0.38991 (18)	0.53223 (17)	0.0181 (4)
H6A	0.7600	0.3096	0.4820	0.022*
H6B	0.8889	0.3868	0.6040	0.022*
C11	0.7387 (3)	0.62442 (17)	0.89147 (16)	0.0150 (3)
C12	0.9383 (3)	0.69368 (19)	0.89847 (18)	0.0184 (3)
H12	1.0433	0.6743	0.8406	0.022*
C13	0.9771 (3)	0.7920 (2)	0.9933 (2)	0.0219 (4)
H13	1.1094	0.8390	0.9991	0.026*
C14	0.8192 (3)	0.82122 (19)	1.08054 (19)	0.0213 (4)
H14	0.8456	0.8881	1.1430	0.026*
C15	0.6222 (3)	0.74957 (19)	1.07324 (18)	0.0207 (4)
H15	0.5180	0.7678	1.1320	0.025*
C16	0.5811 (3)	0.65069 (18)	0.97815 (17)	0.0179 (3)
H16	0.4496	0.6029	0.9728	0.022*
C51	0.5767 (3)	0.40107 (19)	0.24595 (18)	0.0238 (4)
H51A	0.7157	0.3597	0.2350	0.036*
H51B	0.5002	0.4246	0.1583	0.036*
H51C	0.4848	0.3429	0.2898	0.036*
C52	1.0692 (3)	0.5636 (2)	0.2934 (2)	0.0261 (5)
H52A	1.2296	0.5671	0.3019	0.039*	0.50
H52B	1.0115	0.6480	0.3082	0.039*	0.50
H52C	1.0112	0.5345	0.2038	0.039*	0.50
H52D	0.9385	0.5993	0.2407	0.039*	0.50
H52E	1.1567	0.5184	0.2344	0.039*	0.50
H52F	1.1570	0.6319	0.3388	0.039*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P2	0.01357 (18)	0.0145 (2)	0.01400 (17)	−0.00016 (17)	0.00066 (12)	−0.00024 (18)
O1	0.0223 (6)	0.0116 (6)	0.0183 (6)	−0.0015 (5)	0.0029 (5)	−0.0013 (5)
O3	0.0187 (6)	0.0128 (6)	0.0166 (6)	0.0028 (5)	0.0042 (5)	0.0017 (5)
O21	0.0141 (5)	0.0317 (9)	0.0190 (5)	0.0004 (5)	0.0023 (4)	−0.0017 (6)
O22	0.0181 (5)	0.0146 (6)	0.0160 (5)	0.0013 (5)	−0.0018 (4)	−0.0024 (5)
O51	0.0153 (5)	0.0162 (7)	0.0152 (5)	0.0021 (5)	−0.0014 (4)	−0.0021 (5)
O52	0.0157 (6)	0.0360 (8)	0.0205 (6)	0.0100 (5)	0.0046 (5)	0.0027 (6)
C4	0.0136 (7)	0.0156 (8)	0.0195 (8)	−0.0024 (6)	0.0030 (6)	0.0004 (7)
C5	0.0118 (6)	0.0201 (10)	0.0150 (7)	0.0037 (6)	0.0012 (5)	−0.0007 (6)
C6	0.0216 (8)	0.0161 (9)	0.0160 (8)	0.0058 (7)	0.0006 (6)	−0.0009 (7)
C11	0.0172 (7)	0.0127 (8)	0.0143 (7)	0.0020 (6)	−0.0012 (6)	−0.0001 (6)
C12	0.0154 (7)	0.0216 (9)	0.0185 (7)	0.0014 (6)	0.0029 (6)	0.0008 (7)
C13	0.0209 (9)	0.0218 (10)	0.0221 (8)	−0.0029 (7)	−0.0007 (7)	−0.0018 (7)
C14	0.0252 (8)	0.0197 (10)	0.0176 (8)	0.0055 (7)	−0.0027 (7)	−0.0035 (7)
C15	0.0210 (8)	0.0256 (10)	0.0154 (7)	0.0076 (7)	0.0019 (6)	0.0005 (7)
C16	0.0170 (7)	0.0207 (9)	0.0156 (7)	0.0009 (6)	0.0004 (6)	0.0020 (7)
C51	0.0319 (9)	0.0184 (9)	0.0193 (8)	−0.0013 (7)	−0.0032 (7)	−0.0034 (7)
C52	0.0174 (8)	0.0362 (13)	0.0263 (9)	−0.0012 (7)	0.0083 (7)	−0.0056 (8)

Geometric parameters (Å, º)

P2—O1	1.5713 (14)	C12—C13	1.386 (3)
P2—O3	1.5733 (14)	C12—H12	0.93
P2—O21	1.4579 (13)	C13—C14	1.401 (3)
P2—O22	1.5986 (12)	C13—H13	0.93
O1—C6	1.454 (2)	C14—C15	1.394 (3)
O3—C4	1.462 (2)	C14—H14	0.93
O22—C11	1.408 (2)	C15—C16	1.393 (3)
O51—C5	1.409 (2)	C15—H15	0.93
O51—C51	1.431 (2)	C16—H16	0.93
O52—C5	1.407 (2)	C51—H51A	0.96
O52—C52	1.440 (2)	C51—H51B	0.96
C4—C5	1.530 (2)	C51—H51C	0.96
C4—H4A	0.97	C52—H52A	0.96
C4—H4B	0.97	C52—H52B	0.96
C5—C6	1.531 (2)	C52—H52C	0.96
C6—H6A	0.97	C52—H52D	0.96
C6—H6B	0.97	C52—H52E	0.96
C11—C16	1.389 (3)	C52—H52F	0.96
C11—C12	1.394 (2)
O1—P2—O21	114.89 (8)	C14—C13—H13	119.7
O1—P2—O3	106.57 (7)	C15—C14—C13	119.67 (18)
O1—P2—O22	100.98 (7)	C15—C14—H14	120.2
O3—P2—O21	112.00 (8)	C13—C14—H14	120.2
O3—P2—O22	106.24 (7)	C16—C15—C14	120.16 (17)
O21—P2—O22	115.13 (7)	C16—C15—H15	119.9
C6—O1—P2	117.91 (11)	C14—C15—H15	119.9
C4—O3—P2	120.04 (11)	C11—C16—C15	119.21 (17)
C11—O22—P2	120.64 (11)	C11—C16—H16	120.4
C5—O51—C51	115.20 (13)	C15—C16—H16	120.4
C5—O52—C52	115.31 (14)	O51—C51—H51A	109.5
O3—C4—C5	110.12 (13)	O51—C51—H51B	109.5
O3—C4—H4A	109.6	H51A—C51—H51B	109.5
C5—C4—H4A	109.6	O51—C51—H51C	109.5
O3—C4—H4B	109.6	H51A—C51—H51C	109.5
C5—C4—H4B	109.6	H51B—C51—H51C	109.5
H4A—C4—H4B	108.1	O52—C52—H52A	109.5
O52—C5—O51	112.46 (13)	O52—C52—H52B	109.5
O52—C5—C4	111.78 (14)	H52A—C52—H52B	109.5
O51—C5—C4	105.13 (13)	O52—C52—H52C	109.5
O52—C5—C6	103.03 (13)	H52A—C52—H52C	109.5
O51—C5—C6	113.77 (13)	H52B—C52—H52C	109.5
C4—C5—C6	110.87 (14)	O52—C52—H52D	109.5
O1—C6—C5	110.88 (13)	H52A—C52—H52D	141.1
O1—C6—H6A	109.5	H52B—C52—H52D	56.3
C5—C6—H6A	109.5	H52C—C52—H52D	56.3
O1—C6—H6B	109.5	O52—C52—H52E	109.5
C5—C6—H6B	109.5	H52A—C52—H52E	56.3
H6A—C6—H6B	108.1	H52B—C52—H52E	141.1
C16—C11—C12	121.54 (17)	H52C—C52—H52E	56.3
C16—C11—O22	120.62 (15)	H52D—C52—H52E	109.5
C12—C11—O22	117.80 (15)	O52—C52—H52F	109.5
C13—C12—C11	118.73 (17)	H52A—C52—H52F	56.3
C13—C12—H12	120.6	H52B—C52—H52F	56.3
C11—C12—H12	120.6	H52C—C52—H52F	141.1
C12—C13—C14	120.69 (19)	H52D—C52—H52F	109.5
C12—C13—H13	119.7	H52E—C52—H52F	109.5
O1—P2—O3—C4	−41.4 (2)	C52—O52—C5—O51	53.5 (2)
P2—O3—C4—C5	50.1 (2)	C51—O51—C5—O52	61.7 (2)
O3—C4—C5—C6	−55.7 (2)	O3—C4—C5—O52	−170.1 (2)
C4—C5—C6—O1	58.5 (2)	O3—C4—C5—O51	67.6 (2)
C5—C6—O1—P2	−53.9 (2)	O52—C5—C6—O1	178.2 (2)
C6—O1—P2—O3	42.7 (2)	O51—C5—C6—O1	−59.8 (2)
O1—P2—O22—C11	176.70 (12)	P2—O22—C11—C16	70.66 (18)
O3—P2—O22—C11	65.65 (13)	P2—O22—C11—C12	−111.75 (15)
C51—O51—C5—C4	−176.4 (2)	C16—C11—C12—C13	−0.9 (3)
C51—O51—C5—C6	−54.9 (2)	O22—C11—C12—C13	−178.46 (15)
C52—O52—C5—C4	−64.5 (2)	C11—C12—C13—C14	0.1 (3)
C52—O52—C5—C6	176.4 (2)	C12—C13—C14—C15	0.9 (3)
O21—P2—O1—C6	167.3 (1)	C13—C14—C15—C16	−1.0 (3)
O22—P2—O1—C6	−68.1 (2)	C12—C11—C16—C15	0.8 (3)
O21—P2—O3—C4	−167.8 (2)	O22—C11—C16—C15	178.26 (14)
O22—P2—O3—C4	65.7 (2)	C14—C15—C16—C11	0.2 (2)
O21—P2—O22—C11	−58.9 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C14—H14···O21^i	0.93	2.52	3.368 (2)	151
C51—H51C···O3^ii	0.96	2.52	3.414 (3)	155
C4—H4A···O21^iii	0.97	2.49	3.384 (2)	153
C12—H12···O21^iii	0.93	2.52	3.415 (2)	162
C52—H52A···O51^iii	0.96	2.40	3.332 (2)	165

Symmetry codes: (i) −x+1, y+1/2, −z+2; (ii) −x+1, y−1/2, −z+1; (iii) x+1, y, z.