Preparation of Enantioenriched Chiral Organic Molecules by Dynamic Asymmetric Induction from a Outer Chiral Source

Emergence of Highly Enantioselective Catalytic Activity in a Helical Polymer Mediated by Deracemization of Racemic Pendants

“…Surprisingly, the ( S )- and ( R )- 2a NO monomers were catalytically inactive and racemic 2a NO showed no deracemization ability with the chiral alcohol. Asymmetric reactions catalyzed by a racemic monomer-based one-handed helical polymer have no precedent. − The effect of the position of the N -oxide moiety ( 2b NO ) of a PBA on the helicity/axial chirality induction and its static memory as well as that of the ee value of the pendants of poly- 2a NO on the enantioselective catalytic activity were also investigated (Figure c, d).…”

Stereochemical study on planar‐chiral cyclic molecules using polysaccharide‐based column chromatography

“…Further studies on planarchiral cyclic molecules, including dynamic asymmetric induction (DYASIN) using polysaccharide-based chiral stationary phase, are underway. 44,45…”

“…In summary, we described a story of our planar‐chiral cyclic molecules from the beginning until recent, with a central focus on the importance of polysaccharide‐based column chromatography. Further studies on planar‐chiral cyclic molecules, including dynamic asymmetric induction (DYASIN) using polysaccharide‐based chiral stationary phase, are underway 44 , 45 …”

Preparation of enantioenriched helical- and axial-chiral molecules by dynamic asymmetric induction

“…Considering the stereochemical behavior and reactivity of A, we envisaged that it could be prepared in an enantioenriched form via our recently developed À d À ynamic À a À symmetric À i À nduction (DYASIN) method. 9 Namely the racemic form of dynamic chiral heterohelicene A could be converted into the enantioenriched form by thermodynamically controlled isomerization under the chiral environment of an À outer À chiral À source (OCS), such as a chiral polymer or chiral solid material, because the interaction with the OCS will be different between enantiomers of A (step 1 of Fig. 3).…”

“…In this study, we chose polysaccharide-based chiral solid materials as the OCSs, 11 which provided good results in our previous studies of DYASIN of planar chiral molecule. 9 However, as shown in entry 1 of Table 1, DYASIN of the 6,9-non-substituted lactone 2a (Z, Z 0 = H) with cellulose tris(3,5-dichlorophenylcarbamate) (OCS1) 11a in n-C 6 H 14 at 25 1C for 24 h afforded only the racemic form (50% ep) [mole fractions of the major enantiomer are described here as the enantiomeric purity (ep)] (entry 1). Compared to OCS1, amylose tris(3,5-dimethylphenylcarbamate) (OCS2), 11b amylose tris[(S)-a-methylbenzylcarbamate] (OCS3), 11c cellulose tris(4-methylbenzoate) (OCS4), 11d and cellulose tris(3,5dimethylphenylcarbamate) (OCS5) 11e provided better results: they caused DYASIN, although the levels of stereocontrol were low [53% ep (P), 58% ep (P), 64% ep (M) and 63% ep (P), respectively] (entries 2-5).…”