Trans-diaryl epoxides: asymmetric synthesis, ring-opening, and absolute configuration.
Anthryl-phenyl, phenanthryl-phenyl, and naphthyl-phenyl trans-epoxides (1, 2, and 3, respectively) having enantiomeric purities of 95%, 99%, and 96% were synthesized from a diastereo and enantiopure sulfonium salt derived from Eliel's oxathiane. The determination of their (1R,2R) absolute configurations was achieved by application of the CD exciton chirality method using a Zn-porphyrin tweezer on the corresponding alcohols obtained after opening of these epoxides with LiAlH(4). The R-configuration at C2 of these epoxides, (-)-1, (+)-2, and (-)-3, is consistent with our previous results concerning asymmetric synthesis of monoaryl epoxides, cyclopropanes, and aziridines. The (1S,2R)-configuration of the cis isomer (when present) was also confirmed. Moreover, the agreement between the negative exciton chirality for conjugates of (S)-configuration predicted by molecular modeling and the observed CD spectra helps to clarify the relative steric size of phenyl and CH(2)-aryl (phenanthryl or anthryl), which is critical when the tweezer method is applied for absolute configurational assignment (phenyl = medium group; anthacenyl CH(2) and phenanthryl CH(2) = large group).
Solladié-Cavallo
A
A
Laboratoire de stéréochimie organométallique associé au CNRS, ECPM/Université L. Pasteur, 25 rue Becquerel, 67087 Strasbourg, France. cavallo@chimie.u-strasbg.fr
Roje
M
M
Giraud-Roux
M
M
Chen
Y
Y
Berova
N
N
Sunjic
V
V
D000605:Amino Alcohols / Q000138:chemical synthesis / Q000737:chemistry; D004852:Epoxy Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D008722:Methods; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism
D000605:Amino Alcohols; D004852:Epoxy Compounds