(±)-syn-Isopropyl 4-(1,1,1,3,3,3-hexa­fluoro­propan-2-yl­oxy)-1-hydr­oxy-3-methyl-2-(prop-1-yn­yl)cyclo­pent-2-ene­carboxyl­ate

Annika Gille; Markus Schürmann; Hans Preut; Martin Hiersemann

doi:10.1107/S1600536809023162

. 2009 Jun 20;65(Pt 7):o1660. doi: 10.1107/S1600536809023162

(±)-syn-Isopropyl 4-(1,1,1,3,3,3-hexafluoropropan-2-yloxy)-1-hydroxy-3-methyl-2-(prop-1-ynyl)cyclopent-2-enecarboxylate

Annika Gille ^a, Markus Schürmann ^a, Hans Preut ^a,^*, Martin Hiersemann ^a

PMCID: PMC2969198 PMID: 21582922

Abstract

The title compound, C₁₆H₁₈F₆O₄, was obtained through an unprecedented one-pot reaction sequence involving a Gosteli–Claisen rearrangement and a cycloisomerization. The constitution and relative configuration were determined by single-crystal X-ray diffraction analysis. In the crystal, molecules are connected via O—H ⋯ O hydrogen bonds.

Related literature

For the preparation, see: Neises & Steglich (1978 ▶); Hiersemann (2000 ▶). For details of the Gosteli–Claisen rearrangement, see: Gosteli (1972 ▶); Landor & Black (1965 ▶).

Experimental

Crystal data

C₁₆H₁₈F₆O₄
M _r = 388.30
Triclinic,
a = 6.0166 (4) Å
b = 11.9075 (6) Å
c = 13.2798 (8) Å
α = 104.600 (5)°
β = 91.775 (5)°
γ = 96.955 (5)°
V = 912.03 (10) Å³
Z = 2
Mo Kα radiation
μ = 0.14 mm⁻¹
T = 173 K
0.42 × 0.20 × 0.18 mm

Data collection

Oxford Diffraction Xcalibur S CCD diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008 ▶) T _min = 0.944, T _max = 0.975
7349 measured reflections
3175 independent reflections
2089 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.106
S = 0.96
3175 reflections
240 parameters
H-atom parameters constrained
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2008 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2008 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL-Plus (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809023162/hg2521sup1.cif

e-65-o1660-sup1.cif^{(20.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809023162/hg2521Isup2.hkl

e-65-o1660-Isup2.hkl^{(155.7KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O3ⁱ	0.84	2.10	2.8431 (17)	148

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

For the preparation of the title compound (±)-(I) a propargyl vinyl ether (II) was synthesized from 2-butin-1-ol using an etherification with bromoacetic acid, an esterification under Steglich's conditions (Neises & Steglich, 1978) and an aldol condensation (Hiersemann, 2000). An unprecedented one-pot reaction sequence involving an uncatalyzed Gosteli-Claisen rearrangement (Gosteli, 1972) of the propargyl vinyl ether (II) (Landor & Black, 1965) and a cycloisomerization under incorporation of a solvent molecule provided (I) as a colourless solid. Fig. 1 depicts the constitution and relative configuration of the isolated diastereomer (I).

Experimental

The title compound (I) was synthesized according to the following procedure. A solution of (II) (0.044 g, 0.2 mmol) in dry hexafluoroisopropanol (0.6 ml) was stirred at 333 K for 23 h. The solvent was removed under reduced pressure. Flash chromatography (isohexane/ethyl acetate 100/1 to 50/1 to 20/1) afforded (I) as a single diastereomer (0.026 g, 0.07 mmol, 34%) and 37% of the starting material (II). Single crystals of (I) were obtained by vapor diffusion recrystallization technique from isohexane and ethyl acetate to yield colorless cuboids: mp 385 K; R_f 0.32 (cyclohexane/ethyl acetate 5/1); ¹H NMR (CDCl₃, 400 MHz, δ): 1.23 (d, J = 6.3 Hz, 3H, 8-H), 1.26 (d, J = 6.3 Hz, 3H, 8-H), 1.91 (s, 3H, 12-H), 2.01 (s, 3H, 11-H), 2.03 (dd, J = 13.6, 5.9 Hz, 1H, 5-H), 2.86 (dd, J = 13.6, 7.0 Hz, 1H, 5-H), 3.76 (br.s, 1H, –OH), 4.23 (sep, J = 5.9 Hz, 1H, 13-H), 4.67 (t, J = 5.9 Hz, 1H, 4-H), 5.06 (sep, J = 6.3 Hz, 1H, 7-H); ¹⁹F NMR (CDCl₃, 282 MHz, δ): (-77.0)-(-76.7) (m, 6 F); ¹³C NMR (CDCl₃, 101 MHz, δ): 4.8 (11-CH₃), 13.3 (12-CH₃), 21.7 (8-CH₃), 21.8 (8-CH₃), 42.7 (5-CH₂), 70.6 (7-CH), 71.6 (9-C), 76.0 (sep, J = 32.6 Hz, 13-CH), 83.1 (1-C), 88.9 (4-CH), 94.5 (10-C), 121.2 (q, J = 283.0 Hz, 14-C), 121.8 (q, J = 283.0 Hz, 14-C), 126.5 (2-C), 146.9 (3-C), 173.6 (6-C); IR (cm^-1): 3485(br,s) (ν O—H, OH in H-bridges), 2990(m) 2940(m) 2920(m) (ν_as,s C—H, CH₂, CH₃, CH), 2230(w) (ν C≡C), 1715(s) (ν C=O, ester), 1635(m) (ν C=C), 1380(m) (δ_s C—H, CH₃), 1295(s) (ν C—O, ester), 1240(s) 1230(s) 1220(s) (ν C—F), 1185(s) 1120(s) 1105(s) (ν C—O, ether); Anal. Calcd. for C₁₆H₁₈F₆O₄: C,49.5; H, 4.7; Found: C, 49.1; H, 4.7; M = 388.30 g/mol.