Crystal structure of ethyl 2-(di­eth­oxy­phosphor­yl)-2-(2,3,4-tri­meth­oxy­phen­yl)acetate

Moritz Schubert; Dieter Schollmeyer; Siegfried R Waldvogel

doi:10.1107/S1600536814015803

. 2014 Aug 1;70(Pt 9):o897–o898. doi: 10.1107/S1600536814015803

Crystal structure of ethyl 2-(diethoxyphosphoryl)-2-(2,3,4-trimethoxyphenyl)acetate

Moritz Schubert ^a, Dieter Schollmeyer ^a, Siegfried R Waldvogel ^a,^*

PMCID: PMC4186086 PMID: 25309241

Abstract

The title compound, C₁₇H₂₇O₈P, was prepared by Michaelis–Arbuzov reaction of ethyl 2-bromo-2-(2,3,4-trimethoxyphenyl)acetate and triethyl phosphite. Such compounds rarely crystallize, but single crystals were recovered after the initial oil was left for approximately 10 years. The bond angle of the sp ³-hybridized C atom connecting the benzene derivative with the phospho unit is widened marginally [112.5 (2)°]. The terminal P—O bond length of 1.464 (2) Å clearly indicates a double bond, whereas the two O atoms of the ethoxy groups connected to the phosphorous atom have bond lengths of 1.580 (2) Å and 1.581 (3) Å. The three methoxy groups emerge out of the benzene-ring plane due to steric hindrance [C—C—O—C torsion angles = −179.9 (3)°, −52.9 (4)° and 115.3 (4)°]. In the crystal, inversion dimers linked by pairs of C—H⋯O=P hydrogen bonds generate R ₂ ²(14) loops. The chosen crystal was modelled as a non-merohedral twin.

Keywords: crystal structure, Michaelis–Arbuzov reaction, phosphonoacetate, non-merohedral twin, hydrogen bonds

Related literature

For the complete synthesis sequence starting from the corresponding benzene derivative, see: Ianni & Waldvogel (2006 ▶). For the use of the title compound as crucial intermediate in a novel synthetic route for the preparation of phenanthrene carboxylates, see: Schubert et al. (2014 ▶); Wehming et al. (2014 ▶). For the Michaelis–Arbuzov reaction, see: Michaelis & Kaehne (1898 ▶). For a related structure, see: Negrimovsky et al. (2013 ▶).

Experimental

Crystal data

C₁₇H₂₇O₈P
M _r = 390.35
Monoclinic,
a = 9.6314 (14) Å
b = 23.749 (4) Å
c = 8.8155 (14) Å
β = 104.117 (4)°
V = 1955.5 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.18 mm⁻¹
T = 173 K
0.64 × 0.39 × 0.06 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (TWINABS; Sheldrick, 2008b ▶) T _min = 0.615, T _max = 0.746
3859 measured reflections
3859 independent reflections
3033 reflections with I > 2σ(I)
R _int = 0.050

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.137
S = 1.07
3859 reflections
236 parameters
H-atom parameters constrained
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.43 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS2014 (Sheldrick, 2008a ▶); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2008a ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536814015803/hb7246sup1.cif

e-70-0o897-sup1.cif^{(284.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814015803/hb7246Isup2.hkl

e-70-0o897-Isup2.hkl^{(211.8KB, hkl)}

Click here for additional data file.^{(7.5KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814015803/hb7246Isup3.cml

Click here for additional data file.^{(1.2MB, tif)}

I . DOI: 10.1107/S1600536814015803/hb7246fig1.tif

View of compound I. Displacement ellipsoids are drawn at the 50% probability level.

CCDC reference: 1012505

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯O19ⁱ	0.95	2.43	3.379 (4)	179

Open in a new tab

Symmetry code: (i) Inline graphic .

supplementary crystallographic information

S1. Experimental

The title compound was prepared by heating ethyl 2-bromo-2-(2,3,4-trimethoxyphenyl)acetate (13.62 g, 40.9 mmol) with triethyl phosphite (7.4 ml, 43.4 mmol) to reflux for 2 h under inert conditions. After the reaction was cooled to room temperature H₂O (20 ml) was added. The mixture was extracted with ethyl acetate (5 x 40 ml), the combined organic layer was washed with sat. NaCl solution (2 x 20 ml), dried over Na₂SO₄ and concentrated in vacuo. Further purification was achieved by a short-path distillation removing the excess of reagent followed by a short column chromatography using a ethyl acetate-cyclohexane mixture (40:60) as eluent. Analytically pure title compound was isolated as a colorless oil (15.67 g, 40.1 mmol, 98%). Partial crystallization of the colorless oil was observed approximately 10 years after preparation of the title compound. The storage of the material was done at ambient conditions and in absence of light. For further analytical data of the title compound, see: Ianni & Waldvogel (2006).