Crystal structure of 3,4-dihydro-3-oxo-6-ethoxycarbonyl-2H-1,4- benzoxazine-2-acetate, C15H17NO6

C15H17NO6, triclinic, P1 (no. 2), a = 7.6096(3) A, b = 8.3617(5) A, c = 12.3169(5) A, * = 80.681(4)°, ) = 84.982(3)°, & = 84.376(4)°, V = 767.6 A, Z = 2, Rgt(F) = 0.049, wRref(F) = 0.169, T = 290 K. Source of material The title compound synthesis was described and published previously [1]. The crystals for X-ray studies were obtained from ethanol solution by slow solvent evaporation. Experimental details The end-standing methyl (C35) and ethyl (C73, C74) groups are disordered. The occupancy factors for disordered atoms were refined as 0.56(1) for C35 and 0.59(1) for C73’ and C74’ atoms. At the final stage they were fixed as 0.60 and 0.40 for respective pair of atoms in both disordered fragments. Discussion Benzo[b][1,4]oxazin-3(4H)-ones are an important class of heteroaromatic ring systems that have shown awide range of biological activities [2]. As part of our investigations of the relationship between structure and bioactivity [1], we have synthesized a series of 3,4-dihydro-2H-benzo[b][1,4]oxazine-3(4H)-one derivatives. In the studied molecule, the six-membered heterocyclic ring adopts envelope conformationwith C2 andC3 atoms in flap position. The deviations of those atoms from the plane, passing through aromatic ring and both heteroatoms, are 0.255 A and 0.730A, respectively.Among 25 hits found inCSD [3] for related compounds, heterocyclic ring exhibits also a screw-boat conformation. There are two aliphatic substituents in the studied structure. First, ethyl carboxylate located at aromatic ring lies almost in the plane of main molecule moiety with maximal outof-plane deviation of 0.527 A for C74. On the other hand, 2ethoxy-2-oxoethyl, the second equatorial substituent in the heteroring, is located under themain plane (minimal deviation for C31 atomequals 0.395A). Moreover, terminal atoms in both substituents (C73, C74 andC35) are disordered in two sites eachwith s.o. f. = 0.60 and 0.40. The crystal packing is governed by strong hydrogen bond N1–H1···O2 = 2.886(2)A joining molecules into centrosymmetric dimers. The crystal structure architecture is supplemented by two C–H···O32 weak hydrogen bonds. The strong one C3–H3···O32 = 3.386A arranged the dimers into columns (with interlayer distance of 4.952 A). Then, that adjacent columns are joined by interaction of C5–H5···O32 = 3.550 A. Both weak intermolecular interactions are based on the oxygen from 2-ethoxy-2-oxoethyl substituents. Z. Kristallogr. NCS 225 (2010) 531-532 / DOI 10.1524/ncrs.2010. 0233 531 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless prism, size 0.07 × 0.22 × 0.6 mm Wavelength: Mo K* radiation (0.71073 A) -: 1.04 cm−1 Diffractometer, scan mode: Kuma KM-4 CCD, % 2+max: 50° N(hkl)measured, N(hkl)unique: 17686, 2677 Criterion for Iobs, N(hkl)gt: Iobs > 2 ((Iobs), 2152 N(param)refined: 233 Programs: SHELXTL [4], Mercury [5], PLATON [6] Table 1. Data collection and handling. H(1) 2i 0.6632 0.5484 0.9487 0.059 H(3) 2i 0.6560 0.9087 1.0576 0.054 H(5) 2i 1.1779 0.8570 1.0288 0.061 H(6) 2i 1.3245 0.8006 0.8652 0.064 H(8) 2i 0.9067 0.5801 0.8015 0.060 H(31A) 2i 0.6164 0.7238 1.2719 0.062 H(31B) 2i 0.6783 0.9005 1.2553 0.062 H(35A) 2i 0.60 0.1059 0.7334 1.4474 0.223 H(35B) 2i 0.60 0.0013 0.7071 1.3484 0.223 H(35C) 2i 0.60 −0.0697 0.8415 1.4203 0.223 H(35D) 2i 0.40 −0.0654 0.8548 1.4278 0.246 H(35E) 2i 0.40 0.0965 0.9113 1.4777 0.246 H(35F) 2i 0.40 0.1042 0.7349 1.4487 0.246 H(73A) 2i 0.40 1.4987 0.8402 0.5486 0.107 H(73B) 2i 0.40 1.4192 0.6835 0.5229 0.107 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site Occ. x y z Uiso