Journal of the American Chemical Society
Communication
provided by the Japan Science and Technology Agency (CREST,
“Development of High-performance Nanostructures for Process
Integration” Area).
Scheme 1. Pd-Catalyzed Asymmetric Hydrosilylation of β-
Methylstyrene Using random-3m(90/410/2) and block-
3m(90/410/2) As Chiral Macromolecular Ligands
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incorporated in the copolymers, enantiomerically highly
enriched products ((S)-product from P-configured random
copolymer; (R)-product from M-configured block copolymer)
could be obtained from the Pd-catalyzed hydrosilylation of β-
methylstyrene. Again, it should be noted that the P-configured
random copolymer-based catalyst and the M-configured block
polymer-based catalyst only differ in the arrangement of the
chiral sergeant monomers, sharing the same composition of
monomers and the same absolute configuration of the chiral
sergeant unit. Further applications of these single-handed helical
poly(quinoxaline-2,3-diyl)s as a new class of chiral materials are
currently investigated in our laboratory, together with mecha-
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from chiral side chains.
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ASSOCIATED CONTENT
* Supporting Information
Experimental procedures and spectral data for the new
compounds. This material is available free of charge via the
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S
(11) We supposed that chiral and achiral homopolymers have different
gmax values, and the copolymers have mean gmax values of them depended
on the composition, namely
x
gmax = (x × gmax + y × gmax y)/(x + y)
AUTHOR INFORMATION
Corresponding Author
where gmaxx and gmaxy are gmax values of chiral and achiral homopolymers,
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x
and x and y are the number of chiral and achiral units, respectively. gmax
was converged to 2.51 × 10−3. gmax of 1m(x/y) and 2m(x/y) were
y
Notes
converged to 2.23 × 10−3 and 2.11 × 10−3, respectively.
(12) Here, ΔGh was defined as the energy difference between pure P-
and M-helical structures. Because ΔGh was defined as the energy
difference between racemic and purely single-handed structures in the
Sato’s paper,5 the doubled values were shown here for clear comparison.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We thank Takumi Adachi and Keisuke Takagi for help with
experiments and analyses. Financial support for this research was
D
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX