368
Y. Morisaki
Fig. 10.32 Simulation results: the transition dipole moments of (S p )-67 and (S p )-51 in the excited
states by using the TD-DFT calculations at the ωB97XD/6-31G(d,p) level of theory with following
options; TD = (NStates = 10, Root = 1), SCRF = (SOLVENT = Chloroform). Lengths of the
dipole moments on the structures are based on the atomic units
10.6 Synthesis of Enantiopure
Bis-(Para)-Pseudo-Meta-Tetrasubstituted
[2.2]Paracyclophane
In 2018, enantiopure bis-(para)-pseudo-meta-tetrasubstituted [2.2]paracyclophane
derivatives were prepared as new chiral building blocks by means of diastereomeric
optical resolution (Sawada et al. 2018). On the other hand, Lützen and coworkers
had already reported the chromatographic optical resolution of disubstituted analogs
in 2014 (Meyer-Eppler et al. 2014). Racemic 4,7,12,15-tetrasubstituted [2.2]paracyclophane rac-33 was used as the starting material, which was reacted with BuLi
to form the dilithiated intermediate rac-68 (Fig. 10.33). After the formation of
lithium phenoxide, the next lithium-halogen exchange occurred at pseudo-metaposition due to the electronic effect, leading to bis-(para)-pseudo-meta-type dilithiated [2.2]paracyclophane. Addition of B(OMe) 3 to the intermediate and the treatment with H 2 O 2 /NaOH resulted in dibromodihydroxy[2.2]paracyclophane rac-69.
Y. Morisaki
Fig. 10.32 Simulation results: the transition dipole moments of (S p )-67 and (S p )-51 in the excited
states by using the TD-DFT calculations at the ωB97XD/6-31G(d,p) level of theory with following
options; TD = (NStates = 10, Root = 1), SCRF = (SOLVENT = Chloroform). Lengths of the
dipole moments on the structures are based on the atomic units
10.6 Synthesis of Enantiopure
Bis-(Para)-Pseudo-Meta-Tetrasubstituted
[2.2]Paracyclophane
In 2018, enantiopure bis-(para)-pseudo-meta-tetrasubstituted [2.2]paracyclophane
derivatives were prepared as new chiral building blocks by means of diastereomeric
optical resolution (Sawada et al. 2018). On the other hand, Lützen and coworkers
had already reported the chromatographic optical resolution of disubstituted analogs
in 2014 (Meyer-Eppler et al. 2014). Racemic 4,7,12,15-tetrasubstituted [2.2]paracyclophane rac-33 was used as the starting material, which was reacted with BuLi
to form the dilithiated intermediate rac-68 (Fig. 10.33). After the formation of
lithium phenoxide, the next lithium-halogen exchange occurred at pseudo-metaposition due to the electronic effect, leading to bis-(para)-pseudo-meta-type dilithiated [2.2]paracyclophane. Addition of B(OMe) 3 to the intermediate and the treatment with H 2 O 2 /NaOH resulted in dibromodihydroxy[2.2]paracyclophane rac-69.