Efficient synthesis of maleimides and carbazoles via Zn(OTf)(2)-catalyzed tandem annulations of isonitriles and allenic esters.
Li, Yuanzhen; Zou, Haixia; Gong, Jianxian; Xiang, Jing; Luo, Tuoping; Quan, Junmin; Wang, Guoxin; Yang, Zhen; Organic letters 9 (2007) 4057–4060; doi:10.1021/ol7018086

data_1505551
_publ_section_title
;
 Efficient synthesis of maleimides and carbazoles via Zn(OTf)(2)-catalyzed
 tandem annulations of isonitriles and allenic esters.
;
_journal_issue                   20
_journal_name_full               'Organic letters'
_journal_page_first              4057
_journal_page_last               4060
_journal_paper_doi               10.1021/ol7018086
_journal_volume                  9
_journal_year                    2007
_chemical_formula_sum            'C23 H20 N2 O4'
_chemical_formula_weight         388.41
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 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                 100.02(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   19.368(4)
_cell_length_b                   14.472(3)
_cell_length_c                   7.2337(14)
_cell_measurement_reflns_used    5900
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25.14
_cell_measurement_theta_min      2.56
_cell_volume                     1996.6(7)
_computing_cell_refinement       Rapid-AUTO
_computing_data_collection       'Rapid-AUTO (Rigaku,2000)'
_computing_data_reduction        'CrystalStructure (Rigaku/MSC,2000)'
_computing_molecular_graphics    'Siemens SHELXTL V4.2,(Sheldrick,1990)'
_computing_publication_material  SHELXL-97,(Sheldrick,1997)
_computing_structure_refinement  SHELXL-97,(Sheldrick,1997)
_computing_structure_solution    SHELXS-97,(Sheldrick,1997)
_diffrn_ambient_temperature      293(2)
_diffrn_detector_area_resol_mean 10.00
_diffrn_measured_fraction_theta_full 0.919
_diffrn_measured_fraction_theta_max 0.919
_diffrn_measurement_device_type  'Rigaku RAXIS RAPID IP'
_diffrn_measurement_method       \W
_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  0.0799
_diffrn_reflns_av_sigmaI/netI    0.1288
_diffrn_reflns_limit_h_max       22
_diffrn_reflns_limit_h_min       -22
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -17
_diffrn_reflns_limit_l_max       8
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            5900
_diffrn_reflns_theta_full        25.14
_diffrn_reflns_theta_max         25.14
_diffrn_reflns_theta_min         2.56
_diffrn_standards_decay_%        0
_diffrn_standards_interval_count 0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.089
_exptl_absorpt_correction_T_max  0.991
_exptl_absorpt_correction_T_min  0.969
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details
; 
                                  HIGASHI, T. (1995). Abscor-Empirical
                                  Absorption Correction based on Fourier
                                  Series Approximation.
                                  Rigaku Corporation,Tokyo,Japan.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.292
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             816
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.145
_refine_diff_density_min         -0.132
_refine_diff_density_rms         0.032
_refine_ls_extinction_coef       0.0200(8)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.003
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     263
_refine_ls_number_reflns         3296
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.003
_refine_ls_R_factor_all          0.1378
_refine_ls_R_factor_gt           0.0441
_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^)+(0.0180P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0668
_refine_ls_wR_factor_ref         0.0728
_reflns_number_gt                1324
_reflns_number_total             3296
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol7018086-file002.cif
_cod_data_source_block           a
_cod_original_sg_symbol_H-M      P2(1)/c
_cod_database_code               1505551