tert-Butyl 2-methyl-2-(4-methyl­benzo­yl)propanoate

Graham B Gould; Brock G Jackman; Marshall W Logue; Rudy L Luck; Louis R Pignotti; Adrian R Smith; Nicholas M White

doi:10.1107/S1600536810003144

. 2010 Jan 30;66(Pt 2):o491–o492. doi: 10.1107/S1600536810003144

tert-Butyl 2-methyl-2-(4-methylbenzoyl)propanoate

Graham B Gould ^a, Brock G Jackman ^a, Marshall W Logue ^a, Rudy L Luck ^a,^*, Louis R Pignotti ^a, Adrian R Smith ^a, Nicholas M White ^a

PMCID: PMC2979969 PMID: 21579897

Abstract

The title compound, C₁₆H₂₂O₃, is bent with a dihedral angle of 75.3 (1)° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C). In the crystal, the molecules are linked into infinite chains held together by weak C—H⋯O hydrogen-bonded interactions between an H atom on the benzene ring of one molecule and an O atom on the ketone functionality of an adjacent molecule. The chains are arranged with neighbouring tert-butyl and dimethyl groups on adjacent chains exhibiting hydrophobic stacking, with short C—H⋯H—C contacts (2.37 Å) between adjacent chains

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 ▶; Logue 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 ▶). For H⋯H interactions, see: Alkorta et al. (2008 ▶).

Experimental

Crystal data

C₁₆H₂₂O₃
M _r = 262.34
Orthorhombic,
a = 8.605 (3) Å
b = 11.659 (3) Å
c = 31.347 (9) Å
V = 3144.9 (16) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 291 K
0.50 × 0.30 × 0.10 mm

Data collection

Enraf–Nonius TurboCAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.969, T _max = 0.988
4411 measured reflections
2758 independent reflections
1334 reflections with I > 2σ(I)
R _int = 0.027
3 standard reflections every 166 min intensity decay: 2%

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.134
S = 1.01
2758 reflections
178 parameters
H-atom parameters constrained
Δρ_max = 0.14 e Å⁻³
Δρ_min = −0.13 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: 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 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810003144/zl2266sup1.cif

e-66-0o491-sup1.cif^{(17.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810003144/zl2266Isup2.hkl

e-66-0o491-Isup2.hkl^{(132.7KB, 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
C3—H3⋯O9ⁱ	0.93	2.71	3.407 (3)	133

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Symmetry code: (i) Inline graphic .

Acknowledgments

Financial assistance from the Chemistry Department of Michigan Technological University is acknowledged.

supplementary crystallographic information

Comment

Treatment of 2,2-disubstituted t-butyl beta-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 tolyl derivative. This is the second paper in a series of four dealing with substituted derivatives (H–, CH₃– (this paper), 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 phenyl ring and a plane composed of the ester functionality of 75.3 (1)°. Molecules are linked by C—H···O weak hydrogen bonds generating infinite chains parallel to the b axis as shown in Fig. 2. The aromatic rings are not involved in intercalation of stacking interactions either within or between the chains. The chains are arranged with neighbouring t-butyl and dimethyl groups on adjacent chains exhibiting hydrophobic stacking with short C—H···H—C contacts between adjacent chains, Fig. 2 (Alkorta et al., 2008).

Experimental

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): 3003 (w, C—H), 2974, 1734 (v.s., ester C=O), 1671 (v.s., ketone C=O) 1608 (m, C—C), 1455 (m), 1386 (m), 1366 (s), 1273 (s, alkyl methyl C—H), 1247 (s), 1130 (v.s., ester C—O), 986 (s), 921 (m), 836 (s, C—H bend), 740 (s). ¹H NMR (CDCl₃) δ; 1.28 (s, 9H), 1.47 (s, 6H), 2.37 (s, 3H), 7.19 (d, 2H, J=8.0 Hz), 7.76 (d, 2H, J=8.8 Hz). ¹³C NMR (CDCl₃) δ; 21.7, 24.1, 27.8, 54.1, 81.8, 129.2, 132.9, 143.5, 174.4, 198.9.