Tomoko Suzuki

Publications (4)19.21 Total impact

• Article: Highly stereoselective synthesis of functionalized beta,beta-di- and trisubstituted vinylic sulfoxides by Cu-catalyzed conjugate addition of organozinc reagents.

  Naoyoshi Maezaki, Hiroaki Sawamoto, Tomoko Suzuki, Ryoko Yoshigami, Tetsuaki Tanaka
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  ABSTRACT: beta,beta-Disubstituted chiral vinylic sulfoxides bearing functionalities have been synthesized via Cu-catalyzed conjugate addition of organozinc reagents to chiral 1-alkynyl sulfoxides. Due to the availability of functionalized organozinc reagents and high syn-selectivity of the reaction, both geometric beta,beta-disubstituted vinylic sulfoxides were selectively synthesized. Furthermore, 1-alkynyl sulfoxides were derivatized into trisubstituted vinylic sulfoxides by trapping the resulting alpha-sulfinyl vinylic carbanion with electrophiles. Highly diastereoselective THF and THP ring formations were accomplished by means of this methodology followed by an intramolecular Michael addition.
  The Journal of Organic Chemistry 12/2004; 69(24):8387-93. · 4.45 Impact Factor
• Source

  Available from: Hirofumi Ohishi

  Article: Asymmetric intramolecular michael addition of alpha-sulfinyl vinylic carbanion to enoates.

  Naoyoshi Maezaki, Hiroaki Sawamoto, Sachiko Yuyama, Ryoko Yoshigami, Tomoko Suzuki, Mayuko Izumi, Hirofumi Ohishi, Tetsuaki Tanaka
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  ABSTRACT: The first example of an asymmetric intramolecular Michael addition reaction with use of alpha-lithiated vinylic sulfoxide as a Michael donor is reported. Michael addition of the alpha-lithiated vinylic sulfoxide to (Z)-enoates proceeds with high diastereoselectivity to give the adducts with (R)-configuration at the beta-position of the ester in the five-membered-ring formation. The selectivity was reversed in the six-membered-ring formation. The resulting ester enolates were reacted with alkyl halides or benzaldehyde with high diastereoselectivity.
  The Journal of Organic Chemistry 10/2004; 69(19):6335-40. · 4.45 Impact Factor
• Article: Pd-catalyzed sulfinylzincation of activated alkynes with 1-alkynyl sulfoxides as a sulfinyl source.

  Naoyoshi Maezaki, Suguru Yagi, Ryoko Yoshigami, Jun Maeda, Tomoko Suzuki, Shizuka Ohsawa, Kouji Tsukamoto, Tetsuaki Tanaka
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  ABSTRACT: Unprecedented Pd-catalyzed sulfinylzincation with 1-alkynyl sulfoxide as a sulfinyl source was developed. Bis-sulfinyl alkenes were formed in good yields on treatment of 1-alkynyl sulfoxides with Et(2)Zn in the presence of a Pd-catalyst, wherein zinc sulfenate (or sulfinylzinc) species would be generated in situ to undergo highly syn-selective conjugate addition to the 1-alkynyl sulfoxides. By using 3,3-dimethyl-1-butynyl sulfoxides, formation of the bis-sulfinyl alkenes was completely suppressed and the sulfinylzincation of activated alkynes was accomplished. The reaction tolerates various functionalities, and was promoted considerably by the neighboring group participation of the heteroatom at the delta-position in the alkynoates. Stereodivergent synthesis of two diastereomeric vinylic sulfoxides and reaction of the resulting vinylzinc species with electrophiles were also described.
  The Journal of Organic Chemistry 08/2003; 68(14):5550-8. · 4.45 Impact Factor
• Article: Geometrically selective synthesis of functionalized beta,beta-disubstituted vinylic sulfoxides by Cu-catalyzed conjugate addition of organozinc reagents to 1-alkynyl sulfoxides.

  Naoyoshi Maezaki, Hiroaki Sawamoto, Ryoko Yoshigami, Tomoko Suzuki, Tetsuaki Tanaka
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  ABSTRACT: [reaction: see text] A new synthetic method of chiral beta,beta-disubstituted vinylic sulfoxides bearing various functionalities has been developed by employing Cu-catalyzed conjugate addition of an organozinc reagent to chiral 1-alkynyl sulfoxide. Since the reaction proceeds with very high syn-selectivity, both geometric beta,beta-disubstituted vinylic sulfoxides were stereoselectively synthesized by changing the combination of 1-alkynyl sulfoxide and the organozinc reagent.
  Organic Letters 05/2003; 5(8):1345-7. · 5.86 Impact Factor