A Straightforward Synthesis of Cyclobutenones via a Tandem Michael Addition/Cyclization Reaction of 2,3-Allenoates with Organozincs
Guobi Chai; Shangze Wu; Chunling Fu; Shengming Ma; Journal of the American Chemical Society 133 (2011) 3740–3743; doi:10.1021/ja1108694

data_4105776
_publ_section_title
;
 A Straightforward Synthesis of Cyclobutenones via a Tandem Michael
 Addition/Cyclization Reaction of 2,3-Allenoates with Organozincs
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              3740
_journal_page_last               3743
_journal_paper_doi               10.1021/ja1108694
_journal_volume                  133
_journal_year                    2011
_chemical_formula_sum            'C18 H16 O'
_chemical_formula_weight         248.31
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 96.700(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   9.0113(12)
_cell_length_b                   9.5129(12)
_cell_length_c                   16.236(2)
_cell_measurement_temperature    296(2)
_cell_volume                     1382.3(3)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_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  0.0222
_diffrn_reflns_av_sigmaI/netI    0.0138
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            15462
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         2.47
_exptl_absorpt_coefficient_mu    0.072
_exptl_absorpt_correction_T_max  1
_exptl_absorpt_correction_T_min  0.792690
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.193
_exptl_crystal_description       block
_exptl_crystal_F_000             528
_exptl_crystal_size_max          0.512
_exptl_crystal_size_mid          0.451
_exptl_crystal_size_min          0.292
_refine_diff_density_max         0.188
_refine_diff_density_min         -0.165
_refine_diff_density_rms         0.034
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.057
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     172
_refine_ls_number_reflns         2435
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.057
_refine_ls_R_factor_all          0.0432
_refine_ls_R_factor_gt           0.0386
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0584P)^2^+0.3343P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1060
_refine_ls_wR_factor_ref         0.1129
_reflns_number_gt                2163
_reflns_number_total             2435
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja1108694_si_002.cif
_cod_data_source_block           z
_cod_database_code               4105776