A general approach to high-yielding asymmetric synthesis of chiral 3-alkyl-4-nitromethylchromans via cascade Barbas-Michael and acetalization reactions.
Ramachary, Dhevalapally B.; Prasad, M. Shiva; Madhavachary, R.; Organic & biomolecular chemistry 9 (2011) 2715–2721; doi:10.1039/c0ob00861c

data_7151759
_publ_section_title
;
 A general approach to high-yielding asymmetric synthesis of chiral
 3-alkyl-4-nitromethylchromans via cascade Barbas-Michael and
 acetalization reactions.
;
_journal_issue                   8
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              2715
_journal_page_last               2721
_journal_paper_doi               10.1039/c0ob00861c
_journal_volume                  9
_journal_year                    2011
_chemical_absolute_configuration unk
_chemical_formula_sum            'C12 H11 N O5'
_chemical_formula_weight         249.22
_chemical_name_systematic
;
?
;
_space_group_IT_number           19
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_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                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   5.6366(2)
_cell_length_b                   12.6433(7)
_cell_length_c                   16.9777(7)
_cell_measurement_reflns_used    2251
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      61.1386
_cell_measurement_theta_min      2.6004
_cell_volume                     1209.92(9)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_detector_area_resol_mean 16.3291
_diffrn_measured_fraction_theta_full 0.986
_diffrn_measured_fraction_theta_max 0.987
_diffrn_measurement_device_type  'Xcalibur, Eos, Gemini'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0659
_diffrn_reflns_av_sigmaI/netI    0.0332
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            2839
_diffrn_reflns_theta_full        61.14
_diffrn_reflns_theta_max         61.22
_diffrn_reflns_theta_min         4.36
_exptl_absorpt_coefficient_mu    0.919
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.53804
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.368
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             520
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.36
_exptl_crystal_size_min          0.28
_refine_diff_density_max         0.394
_refine_diff_density_min         -0.449
_refine_diff_density_rms         0.121
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.1(5)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.118
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     165
_refine_ls_number_reflns         1782
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.118
_refine_ls_R_factor_all          0.0940
_refine_ls_R_factor_gt           0.0920
_refine_ls_shift/su_max          0.024
_refine_ls_shift/su_mean         0.004
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1997P)^2^+0.0807P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2279
_refine_ls_wR_factor_ref         0.2354
_reflns_number_gt                1669
_reflns_number_total             1782
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c0ob00861c.txt
_cod_data_source_block           dbr15a
_cod_database_code               7151759