organic compounds
tert-Butyl 2-benzoyl-2-methylpropanoate
aDepartment of Chemistry, 1400 Townsend Drive, Michigan Technological University, Houghton, MI 49931, USA
*Correspondence e-mail: rluck@mtu.edu
The title compound, C15H20O3, is bent with a dihedral angle of 67.28 (9)° between the mean planes of the phenyl ring and a group encompassing the ester functionality (O=C—O—C). In the crystal, molecules related by inversion symmetry are connected by weak C—H⋯O interactions into infinite chains. On one side of the molecule there are two adjacent interactions between neighbouring molecules involving the H atoms of methyl groups from the dimethyl groups and the O atoms of the ketone; on the other side, there are also two interactions to another adjacent molecule involving the H atoms on the phenyl rings and the carbonyl O atoms of the ester functionality.
Related literature
For the synthesis, spectroscopic characterization and reactivity of the title compound, see: Logue (1974); Logue et al. (1975). For related structures, see: Crosse et al. (2010a,b); Gould et al. (2010). For the syntheses and characterization of structurally similar indanone-derived β-keto ester derivatives, see: Mouri et al. (2009); Noritake et al. (2008); Rigby & Dixon (2008). For weak hydrogen-bonded interactions, see: Karle et al. (2009).
Experimental
Crystal data
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Refinement
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Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).
Supporting information
https://doi.org/10.1107/S1600536810003120/zl2265sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810003120/zl2265Isup2.hkl
Crystals of the material were synthesized as reported earlier and were grown by evaporation of a solution in hexane (Logue, 1974). IR (neat, cm-1): 3439 (br), 3077 (m), 2980 (s), 2938 (m), 1729 (s), 1683 (s), 1598 (m) 1580 (m), 1447 (m), 1388 (m), 1367 (m), 1279 (s), 1156 (s), 987 (m), 928 (m), 845 (m), 796 (m), 709 (s). 1H NMR (CDCl3,) δ: 1.26 (s, 9H), 1.49 (s, 6H), 7.39 (t, 2H, J=6.8 Hz), 7.49 (t, 1H, J=7.6 Hz), 7.85 (d, 2H, J=7.2 Hz). 13C NMR (CDCl3) δ: 24.1, 27.7, 54.3, 81.9, 128.5, 128.9, 132.7, 135.7, 174.2, 198.4.
All H atoms were placed at calculated positions, with C—H = 0.93 Å (aromatic) or 0.96 Å (methyl) and refined using a riding model with Uiso(H) constrained to be 1.5 Ueq(C) for methyl groups and 1.2 Ueq(C) for all other C atoms. The quality of the data as reflected by only 66% of the reflections observed, large ADP's and inaccurate C—C bond lengths is low. The data had been collected on a 30 year old single point detector instrument not equipped with a low temperature device as part of a class project with undergraduate students. Due to the time constraints imposed by the class schedule a maximum exposure time of 60 s had to be alloted for measuring each reflection.
Treatment of 2,2-disubstituted t-butyl β-keto with trifluoroacetic acid at room temperature quantitatively generates the corresponding 2,2-disubstituted β-keto acids, which were used to probe the nature of the transition state for the thermal decarboxylation of β-keto acids (Logue et al., 1975). Structurally similar indanone-derived β-keto ester derivatives have been prepared recently (Mouri et al., 2009; Noritake et al., 2008; Rigby & Dixon, 2008). The directing nature of weak C—H···O H-bonds has been noted to be of importance to afford the three dimensional structure observed in these kinds of molecules (Karle et al., 2009).
In this contribution we present the solid state structure of one such 2,2-disubstituted β-keto acid, i.e. the title compound being the unsubstituted phenyl derivative. This is the first paper in a series of four dealing with substituted derivatives (H– (this paper), CH3–, Cl- and NO2– on the para-position of the phenyl ring) of the title compound. A more detailed comparison of all four substitution compounds will be given in the fourth paper of this series (Crosse et al., 2010a).
The molecule, Fig. 1, displays a bent geometry with a dihedral angle between the mean planes of the phenyl ring and a plane composed of the ester functionality of 67.28 (9)°. Molecules are linked by weak C—H···O hydrogen bonds generating infinite chains parallel to the c axis as shown in Fig. 2. On one side of the molecule there are two adjacent interactions between neighbouring molecules involving H-atoms on methyl groups from the dimethyl moiety and O-atoms on the ketone; on the other side there are also two interactions to another adjacent molecule involving H-atoms on the phenyl rings and the carbonyl O-atoms on the ester functionality.The phenyl rings are not involved in intercalation or stacking interactions either within or between the chains. Instead neighbouring t-butyl groups on adjacent chains exhibit hydrophobic stacking.
For the synthesis, spectroscopic characterization and reactivity of the title compound, see: Logue (1974); Logue et al. (1975). For related structures, see: Crosse et al. (2010a,b); Gould et al. (2010). For the syntheses and characterization of structurally similar indanone-derived β-keto ester derivatives see: Mouri et al. (2009); Noritake et al. (2008); Rigby & Dixon (2008). For weak hydrogen-bonded interactions see: Karle et al. (2009). Paper is 1st in series (ZL2265, ZL2266, ZL2267, ZL2264)
Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell
CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).C15H20O3 | Z = 2 |
Mr = 248.31 | F(000) = 268 |
Triclinic, P1 | Dx = 1.139 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.616 (3) Å | Cell parameters from 25 reflections |
b = 8.696 (3) Å | θ = 10–15° |
c = 11.310 (5) Å | µ = 0.08 mm−1 |
α = 73.25 (4)° | T = 291 K |
β = 72.25 (3)° | Prism, colourless |
γ = 66.05 (3)° | 0.40 × 0.35 × 0.30 mm |
V = 724.3 (5) Å3 |
Enraf–Nonius TurboCAD-4 diffractometer | 1689 reflections with I > 2σ(I) |
Radiation source: Enraf Nonius FR590 | Rint = 0.015 |
Graphite monochromator | θmax = 25.0°, θmin = 1.9° |
non–profiled ω/2τ scans | h = 0→10 |
Absorption correction: ψ scan (North et al., 1968) | k = −9→10 |
Tmin = 0.965, Tmax = 0.979 | l = −12→13 |
2735 measured reflections | 3 standard reflections every 166 min |
2548 independent reflections | intensity decay: 1% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.043 | H-atom parameters constrained |
wR(F2) = 0.119 | w = 1/[σ2(Fo2) + (0.0496P)2 + 0.1543P] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max < 0.001 |
2548 reflections | Δρmax = 0.12 e Å−3 |
164 parameters | Δρmin = −0.12 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008) |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.064 (6) |
C15H20O3 | γ = 66.05 (3)° |
Mr = 248.31 | V = 724.3 (5) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.616 (3) Å | Mo Kα radiation |
b = 8.696 (3) Å | µ = 0.08 mm−1 |
c = 11.310 (5) Å | T = 291 K |
α = 73.25 (4)° | 0.40 × 0.35 × 0.30 mm |
β = 72.25 (3)° |
Enraf–Nonius TurboCAD-4 diffractometer | 1689 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.015 |
Tmin = 0.965, Tmax = 0.979 | 3 standard reflections every 166 min |
2735 measured reflections | intensity decay: 1% |
2548 independent reflections |
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.119 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.12 e Å−3 |
2548 reflections | Δρmin = −0.12 e Å−3 |
164 parameters |
Experimental. Number of psi-scan sets used was 5. Theta correction was applied. Averaged transmission function was used. No Fourier smoothing was applied. |
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 > 2σ(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 | ||
C1 | 1.0848 (3) | −0.3377 (3) | 0.8308 (3) | 0.0843 (7) | |
H1 | 1.1732 | −0.4115 | 0.8727 | 0.101* | |
C2 | 1.1205 (3) | −0.2955 (3) | 0.7023 (3) | 0.0828 (7) | |
H2 | 1.2336 | −0.3389 | 0.6568 | 0.099* | |
C3 | 0.9887 (3) | −0.1880 (3) | 0.6390 (2) | 0.0663 (6) | |
H3 | 1.0133 | −0.1619 | 0.5511 | 0.08* | |
C4 | 0.8198 (2) | −0.1190 (2) | 0.70634 (18) | 0.0499 (5) | |
C5 | 0.7874 (3) | −0.1610 (3) | 0.83672 (19) | 0.0572 (5) | |
H5 | 0.6759 | −0.1144 | 0.8835 | 0.069* | |
C6 | 0.9192 (3) | −0.2718 (3) | 0.8982 (2) | 0.0715 (6) | |
H6 | 0.8953 | −0.3017 | 0.986 | 0.086* | |
C7 | 0.6830 (3) | −0.0021 (3) | 0.63224 (18) | 0.0535 (5) | |
O1 | 0.7093 (2) | −0.0062 (2) | 0.52144 (14) | 0.0808 (5) | |
C8 | 0.5114 (2) | 0.1223 (2) | 0.69448 (18) | 0.0521 (5) | |
C9 | 0.4249 (3) | 0.2636 (3) | 0.5920 (2) | 0.0755 (7) | |
H9B | 0.5024 | 0.3236 | 0.5419 | 0.113* | |
H9C | 0.3191 | 0.3425 | 0.6314 | 0.113* | |
H9A | 0.3993 | 0.2127 | 0.5387 | 0.113* | |
C10 | 0.3865 (3) | 0.0253 (3) | 0.7712 (2) | 0.0707 (6) | |
H10A | 0.3667 | −0.0282 | 0.7166 | 0.106* | |
H10B | 0.2779 | 0.1043 | 0.8075 | 0.106* | |
H10C | 0.4368 | −0.0608 | 0.8375 | 0.106* | |
C11 | 0.5454 (2) | 0.2112 (2) | 0.77688 (18) | 0.0505 (5) | |
O2 | 0.4621 (2) | 0.2339 (2) | 0.88045 (14) | 0.0736 (5) | |
O3 | 0.67818 (16) | 0.26535 (16) | 0.71377 (11) | 0.0533 (4) | |
C12 | 0.7438 (3) | 0.3557 (3) | 0.7690 (2) | 0.0616 (6) | |
C13 | 0.8897 (3) | 0.3905 (4) | 0.6630 (3) | 0.0942 (9) | |
H13A | 0.845 | 0.4548 | 0.5885 | 0.141* | |
H13B | 0.9783 | 0.2838 | 0.6455 | 0.141* | |
H13C | 0.9384 | 0.4551 | 0.6876 | 0.141* | |
C14 | 0.6027 (4) | 0.5217 (3) | 0.7977 (3) | 0.1024 (10) | |
H14A | 0.5558 | 0.5852 | 0.724 | 0.154* | |
H14B | 0.6503 | 0.588 | 0.8214 | 0.154* | |
H14C | 0.512 | 0.4977 | 0.8659 | 0.154* | |
C15 | 0.8130 (4) | 0.2379 (4) | 0.8824 (3) | 0.1046 (10) | |
H15A | 0.8952 | 0.1314 | 0.8593 | 0.157* | |
H15B | 0.7186 | 0.2168 | 0.9482 | 0.157* | |
H15C | 0.8692 | 0.2902 | 0.9121 | 0.157* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0638 (15) | 0.0716 (16) | 0.103 (2) | −0.0149 (12) | −0.0227 (14) | −0.0031 (14) |
C2 | 0.0506 (13) | 0.0702 (15) | 0.104 (2) | −0.0101 (12) | 0.0024 (13) | −0.0182 (14) |
C3 | 0.0647 (14) | 0.0601 (13) | 0.0670 (13) | −0.0244 (12) | 0.0047 (11) | −0.0175 (11) |
C4 | 0.0526 (11) | 0.0448 (10) | 0.0568 (11) | −0.0232 (9) | −0.0039 (9) | −0.0154 (9) |
C5 | 0.0517 (11) | 0.0579 (12) | 0.0588 (12) | −0.0185 (10) | −0.0068 (10) | −0.0128 (10) |
C6 | 0.0676 (15) | 0.0702 (14) | 0.0704 (14) | −0.0210 (12) | −0.0186 (12) | −0.0048 (12) |
C7 | 0.0608 (12) | 0.0618 (12) | 0.0526 (11) | −0.0349 (10) | −0.0080 (9) | −0.0165 (9) |
O1 | 0.0838 (11) | 0.1121 (13) | 0.0602 (10) | −0.0381 (10) | −0.0145 (8) | −0.0314 (9) |
C8 | 0.0507 (11) | 0.0547 (11) | 0.0587 (11) | −0.0244 (9) | −0.0149 (9) | −0.0099 (9) |
C9 | 0.0812 (16) | 0.0708 (15) | 0.0853 (16) | −0.0268 (12) | −0.0395 (13) | −0.0069 (12) |
C10 | 0.0558 (12) | 0.0752 (15) | 0.0921 (16) | −0.0357 (11) | −0.0118 (11) | −0.0172 (12) |
C11 | 0.0473 (11) | 0.0503 (11) | 0.0544 (11) | −0.0187 (9) | −0.0091 (9) | −0.0101 (9) |
O2 | 0.0743 (10) | 0.0925 (11) | 0.0624 (9) | −0.0433 (9) | 0.0091 (8) | −0.0310 (8) |
O3 | 0.0550 (8) | 0.0628 (8) | 0.0547 (8) | −0.0329 (7) | −0.0061 (6) | −0.0173 (6) |
C12 | 0.0660 (13) | 0.0680 (13) | 0.0706 (14) | −0.0348 (11) | −0.0167 (11) | −0.0229 (11) |
C13 | 0.0884 (18) | 0.121 (2) | 0.106 (2) | −0.0729 (18) | −0.0038 (15) | −0.0332 (17) |
C14 | 0.097 (2) | 0.0794 (18) | 0.154 (3) | −0.0341 (16) | −0.0215 (19) | −0.0580 (18) |
C15 | 0.119 (2) | 0.130 (2) | 0.100 (2) | −0.064 (2) | −0.0581 (19) | −0.0060 (18) |
C1—C2 | 1.360 (3) | C9—H9A | 0.96 |
C1—C6 | 1.368 (3) | C10—H10A | 0.96 |
C1—H1 | 0.93 | C10—H10B | 0.96 |
C2—C3 | 1.387 (3) | C10—H10C | 0.96 |
C2—H2 | 0.93 | C11—O2 | 1.197 (2) |
C3—C4 | 1.391 (3) | C11—O3 | 1.336 (2) |
C3—H3 | 0.93 | O3—C12 | 1.479 (2) |
C4—C5 | 1.381 (3) | C12—C15 | 1.504 (3) |
C4—C7 | 1.505 (3) | C12—C14 | 1.507 (3) |
C5—C6 | 1.382 (3) | C12—C13 | 1.514 (3) |
C5—H5 | 0.93 | C13—H13A | 0.96 |
C6—H6 | 0.93 | C13—H13B | 0.96 |
C7—O1 | 1.212 (2) | C13—H13C | 0.96 |
C7—C8 | 1.535 (3) | C14—H14A | 0.96 |
C8—C11 | 1.522 (3) | C14—H14B | 0.96 |
C8—C10 | 1.540 (3) | C14—H14C | 0.96 |
C8—C9 | 1.540 (3) | C15—H15A | 0.96 |
C9—H9B | 0.96 | C15—H15B | 0.96 |
C9—H9C | 0.96 | C15—H15C | 0.96 |
C2—C1—C6 | 120.1 (2) | C8—C10—H10B | 109.5 |
C2—C1—H1 | 119.9 | H10A—C10—H10B | 109.5 |
C6—C1—H1 | 119.9 | C8—C10—H10C | 109.5 |
C1—C2—C3 | 120.2 (2) | H10A—C10—H10C | 109.5 |
C1—C2—H2 | 119.9 | H10B—C10—H10C | 109.5 |
C3—C2—H2 | 119.9 | O2—C11—O3 | 125.43 (18) |
C2—C3—C4 | 120.3 (2) | O2—C11—C8 | 125.07 (17) |
C2—C3—H3 | 119.8 | O3—C11—C8 | 109.46 (16) |
C4—C3—H3 | 119.8 | C11—O3—C12 | 122.50 (15) |
C5—C4—C3 | 118.4 (2) | O3—C12—C15 | 109.11 (18) |
C5—C4—C7 | 123.82 (18) | O3—C12—C14 | 109.65 (17) |
C3—C4—C7 | 117.79 (18) | C15—C12—C14 | 113.7 (2) |
C4—C5—C6 | 120.6 (2) | O3—C12—C13 | 102.51 (16) |
C4—C5—H5 | 119.7 | C15—C12—C13 | 110.8 (2) |
C6—C5—H5 | 119.7 | C14—C12—C13 | 110.4 (2) |
C1—C6—C5 | 120.3 (2) | C12—C13—H13A | 109.5 |
C1—C6—H6 | 119.8 | C12—C13—H13B | 109.5 |
C5—C6—H6 | 119.8 | H13A—C13—H13B | 109.5 |
O1—C7—C4 | 119.24 (19) | C12—C13—H13C | 109.5 |
O1—C7—C8 | 119.62 (19) | H13A—C13—H13C | 109.5 |
C4—C7—C8 | 121.14 (16) | H13B—C13—H13C | 109.5 |
C11—C8—C7 | 110.39 (15) | C12—C14—H14A | 109.5 |
C11—C8—C10 | 111.49 (17) | C12—C14—H14B | 109.5 |
C7—C8—C10 | 109.80 (16) | H14A—C14—H14B | 109.5 |
C11—C8—C9 | 106.87 (16) | C12—C14—H14C | 109.5 |
C7—C8—C9 | 109.79 (17) | H14A—C14—H14C | 109.5 |
C10—C8—C9 | 108.42 (17) | H14B—C14—H14C | 109.5 |
C8—C9—H9B | 109.5 | C12—C15—H15A | 109.5 |
C8—C9—H9C | 109.5 | C12—C15—H15B | 109.5 |
H9B—C9—H9C | 109.5 | H15A—C15—H15B | 109.5 |
C8—C9—H9A | 109.5 | C12—C15—H15C | 109.5 |
H9B—C9—H9A | 109.5 | H15A—C15—H15C | 109.5 |
H9C—C9—H9A | 109.5 | H15B—C15—H15C | 109.5 |
C8—C10—H10A | 109.5 |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···O2i | 0.93 | 2.66 | 3.317 (3) | 128 |
C9—H9A···O1ii | 0.96 | 2.65 | 3.557 (3) | 158 |
Symmetry codes: (i) −x+1, −y, −z+2; (ii) −x+1, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C15H20O3 |
Mr | 248.31 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 291 |
a, b, c (Å) | 8.616 (3), 8.696 (3), 11.310 (5) |
α, β, γ (°) | 73.25 (4), 72.25 (3), 66.05 (3) |
V (Å3) | 724.3 (5) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.40 × 0.35 × 0.30 |
Data collection | |
Diffractometer | Enraf–Nonius TurboCAD-4 |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.965, 0.979 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2735, 2548, 1689 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.119, 1.02 |
No. of reflections | 2548 |
No. of parameters | 164 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.12, −0.12 |
Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008), WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···O2i | 0.93 | 2.66 | 3.317 (3) | 128 |
C9—H9A···O1ii | 0.96 | 2.65 | 3.557 (3) | 157.9 |
Symmetry codes: (i) −x+1, −y, −z+2; (ii) −x+1, −y, −z+1. |
Acknowledgements
Financial assistance from the Chemistry Department of Michigan Technological University is acknowledged.
References
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Treatment of 2,2-disubstituted t-butyl β-keto esters with trifluoroacetic acid at room temperature quantitatively generates the corresponding 2,2-disubstituted β-keto acids, which were used to probe the nature of the transition state for the thermal decarboxylation of β-keto acids (Logue et al., 1975). Structurally similar indanone-derived β-keto ester derivatives have been prepared recently (Mouri et al., 2009; Noritake et al., 2008; Rigby & Dixon, 2008). The directing nature of weak C—H···O H-bonds has been noted to be of importance to afford the three dimensional structure observed in these kinds of molecules (Karle et al., 2009).
In this contribution we present the solid state structure of one such 2,2-disubstituted β-keto acid, i.e. the title compound being the unsubstituted phenyl derivative. This is the first paper in a series of four dealing with substituted derivatives (H– (this paper), CH3–, Cl- and NO2– on the para-position of the phenyl ring) of the title compound. A more detailed comparison of all four substitution compounds will be given in the fourth paper of this series (Crosse et al., 2010a).
The molecule, Fig. 1, displays a bent geometry with a dihedral angle between the mean planes of the phenyl ring and a plane composed of the ester functionality of 67.28 (9)°. Molecules are linked by weak C—H···O hydrogen bonds generating infinite chains parallel to the c axis as shown in Fig. 2. On one side of the molecule there are two adjacent interactions between neighbouring molecules involving H-atoms on methyl groups from the dimethyl moiety and O-atoms on the ketone; on the other side there are also two interactions to another adjacent molecule involving H-atoms on the phenyl rings and the carbonyl O-atoms on the ester functionality.The phenyl rings are not involved in intercalation or stacking interactions either within or between the chains. Instead neighbouring t-butyl groups on adjacent chains exhibit hydrophobic stacking.