Observations on the Stereochemistry of Aldol Reaction Products. Crystal and Molecular Structure of erythro-4-(Benzoyloxy)-3-tert-butyl-4-phenyl-butan-2-one

Article abstract of DOI:10.1021/jo00327a018

The crystal and molecular structure of the title compound 3a has been determined from X-ray diffractometer data by direct methods.Crystals are triclinic, space group P1, with α = 8.562 (2) Angstroem, b = 18.722 (3) Angstroem, c = 6.107 (1) Angstroem, α = 93.45 (2) deg, β = 110.0 (1) deg, γ = 90.97 (1) deg, and z = 2.The structure was refined by full-matrix least-squares methods to R = 0.071 for 1906 observed reflections and confirmed that 3a is the erythro isomer.The stereochemical assignments for the β-hydroxy ketones 1a and 1b based on 1H NMR vicinal couplingconstants are incorrect and caution is advised in assigning β-hydroxy ketone stereochemistry only on the basis of coupling constants especially in situations where the chiral α-carbon contains a bulky substituent.