DBU-Catalyzed Alkyne-Imidate Cyclization toward 1-Alkoxypyrazino[1,2- a]indole Synthesis.
Festa, Alexey A.; Zalte, Rajesh R.; Golantsov, Nikita E.; Varlamov, Alexey V.; Van der Eycken, Erik V.; Voskressensky, Leonid G.; The Journal of organic chemistry 83 (2018) 9305–9311; doi:10.1021/acs.joc.8b01279

data_4035295
_publ_section_title
;
 DBU-Catalyzed Alkyne-Imidate Cyclization toward 1-Alkoxypyrazino[1,2-
 a]indole Synthesis.
;
_journal_issue                   16
_journal_name_full               'The Journal of organic chemistry'
_journal_page_first              9305
_journal_page_last               9311
_journal_paper_doi               10.1021/acs.joc.8b01279
_journal_volume                  83
_journal_year                    2018
_chemical_formula_moiety         'C14 H14 N2 O'
_chemical_formula_sum            'C14 H14 N2 O'
_chemical_formula_weight         226.27
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   18.3046(18)
_cell_length_b                   13.3125(13)
_cell_length_c                   4.6946(5)
_cell_measurement_reflns_used    2352
_cell_measurement_temperature    120(2)
_cell_measurement_theta_max      27.01
_cell_measurement_theta_min      2.23
_cell_volume                     1144.0(2)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'SHELXTL (Sheldrick, 2008)'
_computing_publication_material  'SHELXTL (Sheldrick, 2008)'
_computing_structure_refinement  'SHELXL (Sheldrick, 2015b)'
_computing_structure_solution    'SHELXT (Sheldrick, 2015a)'
_diffrn_ambient_temperature      120(2)
_diffrn_detector_type            'Bruker APEX II CCD area detector'
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Bruker APEX DUO diffractometer'
_diffrn_measurement_method       '\o scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0613
_diffrn_reflns_av_unetI/netI     0.0497
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       25
_diffrn_reflns_limit_h_min       -25
_diffrn_reflns_limit_k_max       18
_diffrn_reflns_limit_k_min       -18
_diffrn_reflns_limit_l_max       6
_diffrn_reflns_limit_l_min       -6
_diffrn_reflns_number            14873
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.988
_diffrn_reflns_theta_min         1.892
_exptl_absorpt_coefficient_mu    0.084
_exptl_absorpt_correction_T_max  0.862
_exptl_absorpt_correction_T_min  0.771
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Bruker SADABS'
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.314
_exptl_crystal_description       needle
_exptl_crystal_F_000             480
_exptl_crystal_size_max          0.340
_exptl_crystal_size_mid          0.180
_exptl_crystal_size_min          0.140
_refine_diff_density_max         0.220
_refine_diff_density_min         -0.210
_refine_diff_density_rms         0.048
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.033
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     157
_refine_ls_number_reflns         3341
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.033
_refine_ls_R_factor_all          0.0595
_refine_ls_R_factor_gt           0.0456
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0547P)^2^+0.0513P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1009
_refine_ls_wR_factor_ref         0.1097
_reflns_Friedel_coverage         0.797
_reflns_Friedel_fraction_full    1.000
_reflns_Friedel_fraction_max     1.000
_reflns_number_gt                2792
_reflns_number_total             3341
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            jo8b01279_si_001.cif
_cod_data_source_block           af24
_cod_database_code               4035295
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.972
_shelx_estimated_absorpt_t_max   0.988
_shelx_res_checksum              96020
_shelx_hkl_checksum              19053