On the [2+2] Cycloaddition of 2-Aminothiazoles and Dimethyl Acetylenedicarboxylate. Experimental and Computational Evidence of a Thermal Disrotatory Ring Opening of Fused Cyclobutenes
Mateo Alajarín; José Cabrera; Aurelia Pastor; Pilar Sánchez-Andrada; Delia Bautista; Journal of Organic Chemistry 71 (2006) 5328–5339; doi:10.1021/jo060664c

data_4021791
_publ_section_title
;
 On the [2+2] Cycloaddition of 2-Aminothiazoles and Dimethyl
 Acetylenedicarboxylate. Experimental and Computational Evidence of a
 Thermal Disrotatory Ring Opening of Fused Cyclobutenes
;
_journal_name_full               'Journal of Organic Chemistry'
_journal_page_first              5328
_journal_page_last               5339
_journal_paper_doi               10.1021/jo060664c
_journal_volume                  71
_journal_year                    2006
_chemical_formula_sum            'C20 H22 N2 O4'
_chemical_formula_weight         354.40
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                96.890(2)
_cell_angle_beta                 103.349(2)
_cell_angle_gamma                96.254(2)
_cell_formula_units_Z            2
_cell_length_a                   8.0947(4)
_cell_length_b                   8.6895(5)
_cell_length_c                   13.3367(7)
_cell_measurement_reflns_used    5078
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      27.92
_cell_measurement_theta_min      2.38
_cell_volume                     897.04(8)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      100(2)
_diffrn_detector_area_resol_mean 8.26
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.993
_diffrn_measurement_device_type  'Bruker SMART APEX'
_diffrn_measurement_method       \w-scan
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0191
_diffrn_reflns_av_sigmaI/netI    0.0242
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            9919
_diffrn_reflns_theta_full        26.00
_diffrn_reflns_theta_max         26.37
_diffrn_reflns_theta_min         2.38
_exptl_absorpt_coefficient_mu    0.092
_exptl_absorpt_correction_T_max  0.9836
_exptl_absorpt_correction_T_min  0.9694
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.312
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             376
_exptl_crystal_size_max          0.34
_exptl_crystal_size_mid          0.24
_exptl_crystal_size_min          0.18
_refine_diff_density_max         0.265
_refine_diff_density_min         -0.192
_refine_diff_density_rms         0.048
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.107
_refine_ls_hydrogen_treatment    'rigid methyls, others riding'
_refine_ls_matrix_type           full
_refine_ls_number_parameters     240
_refine_ls_number_reflns         3629
_refine_ls_number_restraints     7
_refine_ls_restrained_S_all      1.106
_refine_ls_R_factor_all          0.0459
_refine_ls_R_factor_gt           0.0429
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0453P)^2^+0.3230P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1053
_refine_ls_wR_factor_ref         0.1075
_reflns_number_gt                3411
_reflns_number_total             3629
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            jo060664csi20060328_073740.cif
_cod_database_code               4021791