Methyl 4′-isobutyl-2,2′-dimethyl-1,3-dioxo-2,3-dihydro-1H,4′H-spiro­[iso­quinoline-4,5′-oxazole]-4′-carboxyl­ate

Hoong-Kun Fun; Ching Kheng Quah; Kai Xu; Yan Zhang

doi:10.1107/S1600536811019003

. 2011 May 25;67(Pt 6):o1519–o1520. doi: 10.1107/S1600536811019003

Methyl 4′-isobutyl-2,2′-dimethyl-1,3-dioxo-2,3-dihydro-1H,4′H-spiro[isoquinoline-4,5′-oxazole]-4′-carboxylate

Hoong-Kun Fun ^a,^*,^‡, Ching Kheng Quah ^a,^§, Kai Xu ^b, Yan Zhang ^b

PMCID: PMC3120529 PMID: 21754883

Abstract

In the isoquinoline ring system of the title molecule, C₁₉H₂₂N₂O₅, the N-heterocyclic ring is in a half-boat conformation. The dioxa-2-azaspiro ring is essentially planar [maximum deviation = 0.042 (1) Å] and forms a dihedral angle of 81.85 (4)° with the benzene ring. In the crystal, the molecules are linked via intermolecular C—H⋯O hydrogen bonds into chains along [010].

Related literature

For general background to and the potential biological activity of the title compound, see: Pollers-Wieers et al. (1981 ▶); Malamas et al. (1994 ▶); Yu et al. (2010 ▶); Mitchell et al. (1995 ▶, 2000 ▶); Badillo et al. (2010 ▶); Wang et al. (2010 ▶); Nair et al. (2002 ▶); Huang et al. (2011 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶). For standard bond-length data, see: Allen et al. (1987 ▶). For ring conformations, see: Cremer & Pople (1975 ▶). For related structures, see: Fun et al. (2011a ▶,b ▶,c ▶,d ▶).

Experimental

Crystal data

C₁₉H₂₂N₂O₅
M _r = 358.39
Triclinic,
a = 8.6764 (1) Å
b = 8.9366 (1) Å
c = 12.0684 (2) Å
α = 93.495 (1)°
β = 109.892 (1)°
γ = 98.426 (1)°
V = 864.22 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.40 × 0.29 × 0.18 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.961, T _max = 0.982
25638 measured reflections
6231 independent reflections
5381 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.113
S = 1.05
6231 reflections
240 parameters
H-atom parameters constrained
Δρ_max = 0.46 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811019003/rz2597sup1.cif

e-67-o1519-sup1.cif^{(21.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811019003/rz2597Isup2.hkl

e-67-o1519-Isup2.hkl^{(305KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811019003/rz2597Isup3.cml

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
C2—H2A⋯O4ⁱ	0.93	2.56	3.4353 (11)	158
C4—H4A⋯O2ⁱⁱ	0.93	2.56	3.2878 (11)	136
C12—H12C⋯O4ⁱ	0.96	2.59	3.3600 (11)	138

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

HKF and CKQ thank Universiti Sains Malaysia for the Research University Grant (No. 1001/PFIZIK/811160). Financial support from the Program for New Century Excellent Talents in Universities (NCET-08-0271) of China is also acknowledged.

supplementary crystallographic information

Comment

Isoquinolines are often found in bioactive natural products. They have been used to build blocks of benzo[c]phenanthridine alkaloids. (Pollers-Wieers et al., 1981; Malamas et al., 1994; Yu et al., 2010). Isoquinoline-1,3,4-trione and its derivatives have been reported to be redox mediators of photosystems I and have been used as herbicides (Mitchell et al., 2000; 1995). Oxazole rings are also found in some bioactive natural products such as Annuloline and Ostreogrycin A. Spirooxazoles have emerged as attractive synthetic targets because of their potent bioactivity (Badillo et al., 2011; Wang et al.; 2010; Nair et al., 2002). The title compound, which was derived from isoquinoline-1,3,4-trione and oxazoles (Huang et al., 2011), may has a potential use in biochemical and pharmaceutical fields. Due to the importance of the isoquinoline-1,3,4-trione derivatives, we report in this paper the crystal structure of the title compound with a relative configuration of (4S^*, 4'S^*).

In the title racemic compound, Fig. 1, atoms C9 and C10 are the stereo centers. The isoquinoline ring system (N1/C1-C9) is not completely planar, the N-heterocyclic ring (N1/C1/C6-C9) being distorted towards a half-boat conformation with atom C9 deviating by 0.167 (1) Å from the mean plane through the remaining atoms, puckering parameters (Cremer & Pople, 1975) Q = 0.2505 (9) Å, Θ = 114.3 (2)° and φ = 73.8 (2)°. The dioxa-2-azaspiro ring (N2/O3/C9-C11) is essentially planar [maximum deviation of 0.042 (1) Å at atoms C9 and C10] and it inclines at a dihedral angle of 81.85 (4)° with the benzene ring (C1-C6). Bond lengths (Allen et al., 1987) and angles are within normal ranges and comparable to related structures (Fun et al., 2011a,b,c,d).

In the crystal packing (Fig. 2), the molecules are linked via intermolecular C2–H2A···O4, C12–H12C···O4 and C4–H4A···O2 hydrogen bonds (Table 1) into one-dimensional chains along [010].

Experimental

The title compound was the main product from the acid-catalyzed transformation of the photocycloadduct of isoquinoline-1,3,4-trione and 4-isobutyl-5-methoxy-2-methyloxazole. The compound was purified by flash column chromatography with ethyl acetate/petroleum ether (1:4 v/v) as eluents. X-ray quality crystals of the title compound were obtained from slow evaporation of an acetone/petroleum ether solution (1:5 v/v). M.p. 421-423 K.