Ethyl 7-pivaloyl­amino-1,8-naphthyridine-2-carboxyl­ate sesquihydrate

Hoong-Kun Fun; Madhukar Hemamalini; Anita Hazra; Shyamaprosad Goswami

doi:10.1107/S160053681104921X

. 2011 Nov 25;67(Pt 12):o3415. doi: 10.1107/S160053681104921X

Ethyl 7-pivaloylamino-1,8-naphthyridine-2-carboxylate sesquihydrate

Hoong-Kun Fun ^a,^*,^‡, Madhukar Hemamalini ^a, Anita Hazra ^b, Shyamaprosad Goswami ^b

PMCID: PMC3239052 PMID: 22199900

Abstract

In the title hydrate, C₁₆H₁₉N₃O₃·1.5H₂O, both water molecules are disordered: one over two adjacent sites in a 0.498 (5):0.502 (5) ratio and one lying near a crystallographic twofold axis. The dihedral angle between the pyridine rings of the organic moleucle is 1.47 (6)°. In the crystal, the components are linked by N—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds, forming sheets lying parallel to the ac plane.

Related literature

For further details of heterocyclic esters, see: Listvan et al. (2002 ▶); Li et al. (2007 ▶); Goswami & Hazra (2009 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₁₆H₁₉N₃O₃·1.5H₂O
M _r = 656.73
Monoclinic,
a = 30.7759 (7) Å
b = 7.2406 (2) Å
c = 16.9271 (4) Å
β = 120.009 (1)°
V = 3266.32 (14) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.41 × 0.31 × 0.24 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.960, T _max = 0.977
16624 measured reflections
3753 independent reflections
3156 reflections with I > 2σ(I)
R _int = 0.030

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.108
S = 1.04
3753 reflections
228 parameters
H-atom parameters constrained
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.23 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 datablock(s) global, I. DOI: 10.1107/S160053681104921X/hb6505sup1.cif

e-67-o3415-sup1.cif^{(20.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681104921X/hb6505Isup2.hkl

e-67-o3415-Isup2.hkl^{(180.4KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681104921X/hb6505Isup3.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
N3—H1N3⋯O2W	0.85	2.39	3.051 (2)	135
N3—H1N3⋯O1WBⁱ	0.85	2.40	3.095 (3)	140
O1WB—H2WB⋯N2	0.86	2.26	3.077 (3)	160
O2W—H1W2⋯N1ⁱ	0.83	2.13	2.948 (2)	167
C3—H3A⋯O3	0.93	2.23	2.8230 (17)	121

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Symmetry code: (i) Inline graphic .

Acknowledgments

HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University Grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship. SG and AH thank the CSIR [No. 01 (2292)/09/EMR-II], Government of India, for financial support.

supplementary crystallographic information

Comment

Heterocyclic esters are important synthons for the synthesis of different natural products, antimicrobial agents and pharmaceutical compositions (Listvan et al., 2002; Li et al., 2007). The heterocyclic esters are easily synthesized from their corresponding aldehydes by using thiamine hydrochloride as a catalyst in the presence of triethyl amine and alcohol (Goswami & Hazra, 2009). Herein we report the crystal structure of ethyl-7-pivaloylamino-[1,8]naphthyridine-2-carboxylate.

The asymmetric unit of the title compound, Fig. 1, consists of one ethyl-7-pivaloylamino-[1,8]naphthyridine-2-carboxylate molecule, one disordered water molecule over two orientations with a refined occupany ratio of 0.498 (5) : 0.502 (5) and a half-molecule of water (the O2W atom of the water molecule lies near a twofold axis (symmetry code: -x, y, -z+1/2). The dihedral angle between the two pyridine (N1/C1–C5 : N2/C1,C5–C8) rings is 1.47 (6)°.

In the crystal structure, (Fig. 2), the components are connected via intermolecular N—H···O, O—H···N and C—H···O hydrogen bonds (Table 1) to form two-dimensional networks parallel to the ac-plane.

Experimental

Distilled triethylamine (0.6 ml) was added dropwise to a solution of 7-pivaloylamino-[1,8]naphthyridine-2-carbaldehyde (514 mg, 2 mmol) in dry ethanol. Then thiamine hydrochloride (30 mg, 15 mol) was added and the reaction mixture was refluxed for 2.5 h. Excess ethanol was distilled from the reaction mixture after completion of the reaction. Water was added to the reaction mixture and then extracted with chloroform and the organic layer was dried. The crude product was purified through column chromatography (silica gel, 100–200 mesh) eluting with ethyl acetate in petroleum ether (30%) to afford a colorless solid. Yield: 82%. Mp 168–170°C.