title: Reversal of the sense of enantioselectivity between 1- and 2-aza[6]helicenes used as chiral inducers of asymmetric autocatalysis.
abstract: Reversal of the sense of enantioselectivity was observed between 1-aza[6]helicene 2 and 2-aza[6]helicene 3 employed as chiral inducers of asymmetric autocatalysis of pyrimidyl alkanol. In the presence of (P)-(+)-1-aza[6]helicene 2, the reaction of pyrimidine-5-carbaldehyde 1 with diisopropylzinc afforded, in conjunction with asymmetric autocatalysis, (S)-pyrimidyl alkanol 4 with high ee. Surprisingly, the reaction in the presence of (P)-(+)-2-aza[6]helicene 3 gave the opposite enantiomer of (R)-alkanol 4 with high ee. In the same manner, (M)-(-)-2 and (M)-(-)-3 afforded (R)- and (S)-alkanol 4, respectively. The sense of enantioselectivity is controlled not only by the helicity of the azahelicene derivatives but also by the position of the nitrogen atom.
authors.affiliation: Department of Applied Chemistry, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan. soai@rs.kagu.tus.ac.jp and Research Institute of Science and Technology, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan.
authors.forename: Arimasa
authors.initials: A
authors.lastname: Matsumoto
authors.affiliation: Department of Applied Chemistry, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan. soai@rs.kagu.tus.ac.jp.
authors.forename: Kento
authors.initials: K
authors.lastname: Yonemitsu
authors.affiliation: Department of Applied Chemistry, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan. soai@rs.kagu.tus.ac.jp.
authors.forename: Hanae
authors.initials: H
authors.lastname: Ozaki
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic. ivo.stary@uochb.cas.cz stara@uochb.cas.cz.
authors.forename: Jiří
authors.initials: J
authors.lastname: Míšek
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic. ivo.stary@uochb.cas.cz stara@uochb.cas.cz.
authors.forename: Ivo
authors.initials: I
authors.lastname: Starý
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic. ivo.stary@uochb.cas.cz stara@uochb.cas.cz.
authors.forename: Irena G
authors.initials: IG
authors.lastname: Stará
authors.affiliation: Department of Applied Chemistry, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan. soai@rs.kagu.tus.ac.jp and Research Institute of Science and Technology, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601 Japan.
authors.forename: Kenso
authors.identifier: http://orcid.org/0000-0002-8060-444X
authors.initials: K
authors.lastname: Soai