data_1100914 _publ_requested_journal 'Acta Crystallographica C' _publ_section_title ; trans-3-Benzoyl-2-(tert-butyl)-4-(iso-butyl)-1,3-oxazolidin-5-one ; loop_ _publ_author_name 'Willis, Anthony C.' 'Beckwith, Athelstan L.J.' 'Tozer, Matthew J.' _publ_section_abstract ; The oxazolidinone ring is a shallow envelope conformation with the tert-butyl and iso-butyl groups occupying trans-positions with respect to the ring. The angles at the N atom sum to 356.2\%, indicating a very small degree of pyramidalization at this atom. This is consistent with electron delocalization between the N atom and the carbonyl centre [N--C=O = 1.374(3)\%A]. ; _publ_section_comment ; The structure of the title compound was undertaken to establish whether a sec-butyl group would be formed cis or trans to the tert-butyl group as part of a study of diastereoselectivities of free radical reactions. Details of the synthetic work will be published elsewhere (Beckwith, Chai & Tozer, 1991). The tert-butyl and iso-butyl groups are trans, as expected from nmr evidence. The oxazolidinone ring is in an envelope conformation with C(5) the out-of-plane atom. The angle between the least-squares plane through atoms O(1), C(2), C(3) and N(4) and the plane of N(4), C(5) and O(1) is 10.9(2)\%. Intra-annular torsion angles (starting with C(5)-O(1)-C(2)-C(3) and proceeding around the ring) are 9.5, -2.3, -5.4, 10.7 and -12.3(3)\%. A search of the January 1990 Version of the Cambridge Structure Database (Allen, Kennard & Taylor, 1983) revealed three structure determinations with 1,3-oxazolidin-5-one fragments (Seebach, Boes, Naef & Schweizer 1983, Karady, Amato & Weinstock 1984, Weber, Aeschimann, Maetzke & Seebach 1986). Bond lengths and angles in these compounds are comparable with those in the present study; the magnitudes of their respective maximum intra-annular torsion angle are 10.2, 1.9 and 10.2\%. Diagrams and most calculations were performed with the Xtal3.0 package (Hall & Stewart, 1990), as was the generation of the Crystallographic Information File used for the submission of this paper. ; _chemical_name_systematic ; trans-3-Benzoyl-2-(tert-butyl)-4-(iso-butyl)-1,3-oxazolidin-5-one ; _chemical_formula_moiety 'C18 H25 N O3' _chemical_formula_sum 'C18 H25 N O3' _chemical_formula_weight 303.40 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source C ? .017 .009 International_Tables_Vol_IV_Table_2.3.1 H ? 0 0 International_Tables_Vol_IV_Table_2.3.1 O ? .047 .032 International_Tables_Vol_IV_Table_2.3.1 N ? .029 .018 International_Tables_Vol_IV_Table_2.3.1 _symmetry_cell_setting orthorhombic _symmetry_space_group_name_H-M 'P 21 21 21' _symmetry_space_group_name_Hall 'P 2ac 2ab' loop_ _symmetry_equiv_pos_as_xyz 'x,y,z' 1/2-x,-y,1/2+z 1/2+x,1/2-y,-z -x,1/2+y,1/2-z _cell_length_a 5.959(1) _cell_length_b 14.956(1) _cell_length_c 19.737(3) _cell_angle_alpha 90.0 _cell_angle_beta 90.0 _cell_angle_gamma 90.0 _cell_volume 1759.0(3) _cell_formula_units_Z 4 _cell_measurement_temperature 293 _cell_measurement_reflns_used 25 _cell_measurement_theta_min 25 _cell_measurement_theta_max 31 _cell_special_details ; ? ; _exptl_crystal_description prism _exptl_crystal_colour colourless _exptl_crystal_size_max 0.32 _exptl_crystal_size_mid 0.27 _exptl_crystal_size_min 0.10 _exptl_crystal_density_meas 1.146 _exptl_crystal_density_diffrn ? _exptl_crystal_density_method ? _exptl_crystal_F_000 656 _exptl_absorpt_coefficient_mu 0.59 _exptl_absorpt_correction_type 'shelx76 gaussian' _exptl_absorpt_correction_T_min .933 _exptl_absorpt_correction_T_max .824 _diffrn_ambient_temperature 293 _diffrn_radiation_wavelength 1.5418 _diffrn_radiation_type 'Copper K\a' _diffrn_radiation_source xray_tube _diffrn_radiation_monochromator graphite _diffrn_measurement_device 'Philips PW1100/20 diffractometer' _diffrn_measurement_method \q/2\q _diffrn_standards_number 3 _diffrn_standards_interval_count ? _diffrn_standards_interval_time 120 _diffrn_standards_decay_% 0 loop_ _diffrn_standard_refln_index_h _diffrn_standard_refln_index_k _diffrn_standard_refln_index_l 3 2 4 1 9 1 3 0 10 _diffrn_reflns_number 1592 _diffrn_reflns_av_R_equivalents 0 _diffrn_reflns_av_sigmaI/netI .027 _diffrn_reflns_limit_h_min 0 _diffrn_reflns_limit_h_max 6 _diffrn_reflns_limit_k_min -17 _diffrn_reflns_limit_k_max 0 _diffrn_reflns_limit_l_min 0 _diffrn_reflns_limit_l_max 22 _diffrn_reflns_theta_min 3.71 _diffrn_reflns_theta_max 61.97 _diffrn_reflns_reduction_process ? _reflns_number_total ? _reflns_number_observed ? _reflns_observed_criterion ? _refine_ls_structure_factor_coef F _refine_ls_matrix_type full _refine_ls_weighting_scheme '1/(\s^2^(F)+0.0004F^2^)' _refine_ls_hydrogen_treatment 'refxyz except H332B noref' _refine_ls_extinction_method Zachariasen _refine_ls_extinction_coef 3514(42) _refine_ls_extinction_expression 'equ(22) p292 "Crystallographic Computing" (1970)' _refine_ls_abs_structure_details ; The absolute configuration was assigned to agree with the known chirality at C(3) arising from its precursor l-leucine. ; _refine_ls_abs_structure_Flack 0 _refine_ls_number_reflns 1408 _refine_ls_number_parameters 272 _refine_ls_number_restraints 0 _refine_ls_number_constraints 0 _refine_ls_R_factor_all .038 _refine_ls_R_factor_obs .034 _refine_ls_wR_factor_all .044 _refine_ls_wR_factor_obs .042 _refine_ls_goodness_of_fit_all 1.462 _refine_ls_goodness_of_fit_obs 1.515 _refine_ls_shift/esd_max .535 _refine_ls_shift/esd_mean .044 _refine_diff_density_max .131 _refine_diff_density_min -.108 loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_thermal_displace_type _atom_site_calc_flag _atom_site_calc_attached_atom _atom_site_type_symbol O1 .4154(4) .5699(1) .3026(0) .060(1) Uij ? ? O C2 .5630(5) .5087(2) .3246(1) .060(2) Uij ? ? C C3 .5350(5) .4920(2) .3997(1) .048(1) Uij ? ? C N4 .3570(3) .5558(1) .4167(0) .039(1) Uij ? ? N C5 .3000(5) .6122(2) .3581(1) .045(1) Uij ? ? C O21 .6958(5) .4738(2) .2874(1) .090(2) Uij ? ? O C31 .4869(6) .3929(2) .4143(2) .059(2) Uij ? ? C C32 .2552(7) .3558(2) .3953(2) .073(2) Uij ? ? C C321 .209(1) .3542(4) .3211(3) .111(4) Uij ? ? C C322 .230(1) .2626(3) .4264(3) .149(5) Uij ? ? C C41 .2034(4) .5476(2) .4682(1) .041(1) Uij ? ? C O41 .0124(3) .5776(1) .4624(0) .054(1) Uij ? ? O C411 .2826(4) .5093(2) .5334(1) .043(1) Uij ? ? C C412 .1315(5) .4613(2) .5725(1) .064(2) Uij ? ? C C413 .1914(7) .4324(3) .6366(2) .086(2) Uij ? ? C C414 .3987(6) .4522(3) .6620(1) .078(2) Uij ? ? C C415 .5494(6) .4997(2) .6241(1) .065(2) Uij ? ? C C416 .4920(5) .5279(2) .5594(1) .053(2) Uij ? ? C C51 .3745(5) .7097(2) .3634(1) .052(2) Uij ? ? C C511 .6299(6) .7166(3) .3669(2) .072(2) Uij ? ? C C512 .2881(8) .7581(3) .3000(2) .079(2) Uij ? ? C C513 .2757(7) .7522(2) .4267(2) .068(2) Uij ? ? C H3 .679(5) .510(2) .422(1) .06000 Uiso ? ? H H5 .135(5) .608(2) .350(1) .06000 Uiso ? ? H H31A .507(5) .381(2) .461(2) .07000 Uiso ? ? H H31B .593(6) .357(2) .390(2) .07000 Uiso ? ? H H32 .129(6) .401(3) .417(2) .09000 Uiso ? ? H H321A .330(9) .311(4) .306(3) .14000 Uiso ? ? H H321B .22(1) .415(4) .298(2) .14000 Uiso ? ? H H321C .04(1) .318(3) .320(2) .14000 Uiso ? ? H H322A .25(1) .272(4) .475(3) .19000 Uiso ? ? H H322B .34976 .22118 .40954 .19000 Uiso calc C322 H H322C .08(1) .234(4) .397(3) .19000 Uiso ? ? H H412 -.007(6) .447(2) .552(2) .08000 Uiso ? ? H H413 .096(7) .392(3) .661(2) .11000 Uiso ? ? H H414 .447(7) .433(2) .708(2) .10000 Uiso ? ? H H415 .722(6) .521(2) .641(2) .08000 Uiso ? ? H H416 .588(5) .564(2) .535(1) .07000 Uiso ? ? H H511A .683(7) .692(2) .322(2) .09000 Uiso ? ? H H511B .689(6) .681(2) .408(2) .09000 Uiso ? ? H H511C .678(7) .781(3) .372(2) .09000 Uiso ? ? H H512A .143(8) .759(3) .302(2) .10000 Uiso ? ? H H512B .345(7) .726(3) .258(2) .10000 Uiso ? ? H H512C .361(7) .820(3) .302(2) .10000 Uiso ? ? H H513A .337(6) .717(2) .469(2) .09000 Uiso ? ? H H513B .115(7) .757(3) .426(2) .09000 Uiso ? ? H H513C .329(6) .817(2) .430(2) .09000 Uiso ? ? H loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 _atom_site_aniso_type_symbol O1 .071(1) .076(1) .0342(9) .008(1) .0051(9) -.0030(9) O C2 .060(2) .072(2) .047(1) .002(2) .013(1) -.009(1) C C3 .038(1) .060(2) .044(1) .007(1) .001(1) -.005(1) C N4 .037(1) .048(1) .0325(9) .0025(9) .0011(9) -.0011(9) N C5 .043(1) .060(1) .032(1) .001(1) -.001(1) .001(1) C O21 .094(2) .109(2) .068(1) .023(2) .038(1) -.010(1) O C31 .061(2) .056(2) .060(2) .015(2) .005(2) -.002(1) C C32 .075(2) .057(2) .087(2) -.005(2) .002(2) -.018(2) C C321 .100(4) .127(4) .107(3) -.026(3) -.027(3) -.016(3) C C322 .192(7) .084(3) .171(5) -.046(4) -.027(6) .017(3) C C41 .037(1) .046(1) .040(1) -.004(1) .001(1) -.005(1) C O41 .0360(9) .071(1) .054(1) .0066(9) .0028(8) .0015(9) O C411 .042(1) .054(1) .034(1) -.000(1) .002(1) -.003(1) C C412 .048(2) .098(2) .045(1) -.016(2) .003(1) .007(2) C C413 .074(2) .133(3) .052(2) -.022(2) .008(2) .031(2) C C414 .075(2) .118(3) .040(2) -.002(2) -.004(2) .014(2) C C415 .057(2) .096(2) .043(2) -.003(2) -.008(1) -.003(1) C C416 .049(2) .069(2) .041(1) -.010(2) -.001(1) -.002(1) C C51 .048(2) .059(2) .049(1) .002(1) -.000(1) .007(1) C C511 .048(2) .071(2) .097(3) -.008(2) -.003(2) .010(2) C C512 .078(2) .083(2) .075(2) .009(2) -.005(2) .033(2) C C513 .074(2) .055(2) .075(2) .004(2) .001(2) -.010(2) C