98831-01-7Relevant articles and documents
Construction of acyclic all-carbon quaternary stereocenter based on asymmetric michael addition of chiral amine
Niki, Aya,Ozeki, Minoru,Kuse, Akiko,Nakagawa, Shiho,Aoki, Shui,Shigeta, Takashi,Kajimoto, Tetsuya,Iwasaki, Hiroki,Kojima, Naoto,Arimitsu, Kenji,Hosoi, Shinzo,Node, Manabu,Yamashita, Masayuki,Kawasaki, Ikuo
, p. 926 - 930 (2021/09/06)
Acyclic asymmetric quaternary stereocenters, which are composed of four carbon-carbon bonds, were finely constructed by utilizing a face-selective alkylation of enolate intermediates derived from an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-α,β-unsaturated esters. The present face-selective alkylation was able to employ diverse alkyl halides as an electrophile to afford various Michael adducts having an all-carbon quaternary stereocenter. With regard to the deprotection of the chiral auxiliary, N-iodosuccinimide used in our previous study did not work in the present cases; however, we found that pyridine iodine monochloride in the presence of H2O was effective to remove the bornyl group and the benzyl group on the amino group to provide the β-amino ester derivative.
A facile and convenient synthesis of trisubstituted (E)-α,β-unsaturated esters by tandem acetylation-E1CB reaction
Ozeki, Minoru,Hachino, Ayumi,Shigeta, Takashi,Niki, Aya,Kobayashi, Natsuko,Mizutani, Hideki,Nakamura, Akihiro,Horie, Ayano,Arimitsu, Kenji,Kajimoto, Tetsuya,Hosoi, Shinzo,Iwasaki, Hiroki,Kojima, Naoto,Yamashita, Masayuki,Kawasaki, Ikuo
, p. 71 - 74 (2019/01/17)
A facile and convenient synthesis of trisubstituted (E)-α,β-unsaturated esters was developed by improving our previously established method. The new method circumvented the separation of the intermediates, which have an activating group of the hydroxyl group in β-hydroxy esters, furnishing α,β-unsaturated esters in shorter steps than the previous method: an acetylation of β-hydroxy group and subsequent E1cB reaction proceeded in tandem. In addition, the new method can not only employ a diastereomeric mixture of the substrate for the E1cB reaction, it has a wide substrate scope as well, which would enable the synthesis of various trisubstituted (E)-α,β-unsaturated esters.
Novel and practical asymmetric synthesis of β2,3-amino esters using asymmetric Michael addition of chiral amine
Ozeki, Minoru,Egawa, Honoka,Takano, Toshiki,Mizutani, Hideki,Yasuda, Narumi,Arimitsu, Kenji,Kajimoto, Tetsuya,Hosoi, Shinzo,Iwasaki, Hiroki,Kojima, Naoto,Node, Manabu,Yamashita, Masayuki
supporting information, p. 2014 - 2021 (2017/03/20)
A practical method for the synthesis of chiral β2,3-amino esters having various substituents was developed, which is characterized by an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-α,β-unsaturated esters. We found that a highly face-selective protonation occurred by the quick addition of water to the enolate intermediate derived from the Michael addition reaction to afford N-protected β2,3-amino esters in moderate to excellent yields. This finding was made possible by the facile preparation of geometrically pure trisubstituted (E)-α,β-unsaturated esters, which was established recently by our group. The subsequent deprotection of the amino group in the Michael adduct by using N-iodosuccinimide (NIS) efficiently provided β2,3-amino esters having various substituents.
