For most of alkanols where the stereogenic center
generated was in the [gamma] or [delta] position relative to the OH group, the enantiomeric purities of [greater than or equal to] 99% ee were successfully determined by chiral gas chromatography or NMR analysis of Mosher esters.
120) However, enantiomers react differently with chiral reagents because each reacting partner has at least one stereogenic center
that, when combined, produces two complexes which are no longer mirror images of each other.
Spirocyclic systems are widely distributed structural framework, which are structurally interesting due to having one sp3 stereogenic center
that share to two rings .
Moreover, the stereochemistry of stereogenic centers
at C-1, C-3, C-2' and C-3' was deduced by comparing the spectroscopic data of the two ceramides with those of known configuration, since stereochemistry of the ceramide moiety is difficult to determine.
To emphasize the practicality of C-C bond activation, we will prepare in a single-pot operation challenging molecular framework possessing various stereogenic centers
from very simple starting materials through selective C-C bond activation.
Chemists mostly in the US, but also Europe and Asia, explore such aspects as green synthesis of iron nanomaterials for oxidative catalysis of organic environmental pollutants, sorbents and photocatalytic materials for water remediation, the electrochemical promotion of catalysis for automotive post-treatment and air cleaning, catalysts and process design for air pollutants abatement, and asymmetric organocatalysis for constructing quaternary carbon stereogenic centers
It should be noted that there are three stereogenic centers
in each studied compound; therefore the C2(S), C3(S), C4(R)-configuration was suggested for the structures of the obtained molecules.
Among these types of catalysis is the asymmetric phase-transfer catalysis (APTC) which has used quaternary ammonium salts with defined stereogenic centers
of asymmetric induction in organic compounds, for example, the salts (l) and (2) of alkaloids ephedra and (3) and (4) of the Cinchona  (Figure 1) have been used frequently and conducted at good results in terms of stereoselectivity, especially when the substituents in the quaternary nitrogen are bulky.
This study investigated the effect that concentrating stereogenic centers
within a polymer matrix had on the reduction of acetophenone.
The stereochemistry at the stereogenic centers
was determined by the same method as done for 2,3 and was found similar.
The physical properties and the morphology of PVC resins are depending on their microstructures, which are function of the distributions and concentrations of internal double bonds, branches, and the relative configurations of the stereogenic centers
1) are chiraldopants contain stereogenic centers
in one of the side chains.