1. |
Yuuya Kawasaki, Ryota Kamikubo, Yuta Kumegawa, Kouhei Ogawa, Takeru Kashiwagi, Yusuke Ano, Kazunobu Igawa, Katsuhiko Tomooka, Preparation of enantioenriched helical- and axial-chiral molecules by dynamic asymmetric induction, Chemical Communications, 10.1039/d1cc05881a, 58, 10, 1605-1608, 2022.02. |
2. |
Yuuya Kawasaki, Yuki Yamanaka, Yuki Seto, Kazunobu Igawa, Katsuhiko Tomooka, Synthesis of NMs-DACN Small and hydrophilic click reaction device, Chemistry Letters, 10.1246/cl.190026, 48, 5, 495-497, 2019.01, Newly designed small and hydrophilic click reaction devices, NMs-4, 8-diazacyclononynes (NMs-DACNs), have been efficiently synthesized by a one-pot double Nicholas approach. NMs-DACNs react with azides smoothly under copper-free conditions and show higher water solubility than that of previously developed NTs-DACNs.. |
3. |
Jun-ichi Hayashi, Kazuhiro Uehara, Yusuke Ano, Yuuya Kawasaki, Kazunobu Igawa, Katsuhiko Tomooka
, SYNTHESIS AND STEREOCHEMICAL ANALYSIS OF DYNAMIC PLANAR CHIRAL NINE-MEMBERED DIALLYLIC AMIDE: SIGNIFICANT SUBSTITUENT EFFECT ON STEREOCHEMICAL STABILITY, Heterocycles, 10.3987/COM-18-S(F)92, 99, 2019.01. |
4. |
Kazunobu Igawa, Yuuya Kawasaki, Yusuke Ano, Takeru Kashiwagi, Kouhei Ogawa, Jun Ichi Hayashi, Ryota Morita, Yukari Yoshioka, Kazuhiro Uehara, Katsuhiko Tomooka, Preparation of enantioenriched chiral organic molecules by dynamic asymmetric induction from a outer chiral source, Chemistry Letters, 10.1246/cl.190170, 48, 7, 726-729, 2019.01, To obtain enantioenriched chiral organic molecules, numerous optical resolution and asymmetric synthetic methods have been developed to date. Herein, we introduce a new approach termed dynamic asymmetric induction (DYASIN) for the preparation of enantioenriched chiral molecules based on the stereocontrol of dynamic chiral molecules (DYCMs) using an outer chiral source (OCS). DYASIN makes it possible to obtain the enantioenriched form of dynamic chiral molecules from their racemic form without bond cleavage or bond formation. The thus-obtained enantioenriched molecules can be readily converted into a variety of chiral molecules with stable stereochemistries, without any loss of enantiomeric purity.. |
5. |
Kouhei Machida, Yuki Yoshida, Kazunobu Igawa, Katsuhiko Tomooka, Efficient approach to medium-sized cyclic molecules containing (E)-Alkene via z to e photochemical isomerization in the presence of AgNO3-impregnated silica gel, Chemistry Letters, 10.1246/cl.170937, 47, 2, 186-188, 2018.01, Efficient synthesis of medium-sized cyclic molecules containing an (E)-alkene was performed via the highly (E)selective photochemical isomerization of the (Z)-isomer, facilitated by AgNO3-impregnated silica gel.. |
6. |
Kazunobu Igawa, Akihiro Kuroo, Daisuke Yoshihiro, Yuki Yamanaka, Katsuhiko Tomooka, Synthesis of Stereoselectively Functionalized Silacyclopentanes, Synlett, 10.1055/s-0036-1590826, 28, 18, 2445-2448, 2017.11, An efficient approach to a variety of chiral silacyclopentanes having silicon stereogenic center based on the stereospecific transformations of C4 carbon stereogenic center of silacyclopentenols by Mitsunobu reaction or Tsuji-Trost reaction has been developed. The thus obtained substitution products can be converted into novel silacyclopentane triols, amines, and carboxylic acids in stereospecific manner.. |
7. |
Kazunobu Igawa, Shin Aoyama, Yuuya Kawasaki, Takeru Kashiwagi, Yuki Seto, Runyan Ni, Naoto Mitsuda, Katsuhiko Tomooka, One-Pot Synthesis of Versatile Buckle Units for Click Chemistry: 4,8-Diazacyclononynes (DACNs), Synlett, 10.1055/s-0036-1588839, 28, 16, 2110-2114, 2017.01, Newly designed buckle units for copper-free click chemistry: 4,8-diazacyclononynes (DACNs) were efficiently synthesized with a one-pot procedure from commercially available 2-butyne-1,4-diol. The synthesized DACNs possess versatile connectors for the introduction of functional units and exhibit high click reactivity.. |
8. |
Katsuhiko Tomooka, Chemistry of planar chiral medium-sized heterocycles, Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry, 10.5059/yukigoseikyokaishi.75.449, 75, 5, 449-457, 2017.01, Nine-membered E,Z-diallylic heterocycles 1 and [7]-orthocyclphenes 2 exhibit planar chirality at ambient temperature. Their stereochemical stabilities are highly dependent on substituent R1 on the E-Alkene, embedded heteroatom X in the ring, and ring size. Their planar chirality can be transformed into carbon central chirality without loss of enantiopurity. Therefore, they are useful chiral building blocks for biologically active chiral molecules and precursors for chiral reagents. The enantioenriched forms of 1 and 2 are available by optical resolution of racemate, and asymmetric synthesis based on enantioselective cyclization. Planar chiral dialkoxysilane 32 and ketone 33 were also developed.. |
9. |
Kazunobu Igawa, Kouhei Machida, Kyouhei Noguchi, Kazuhiro Uehara, Katsuhiko Tomooka, Synthesis and Stereochemical Analysis of Planar-Chiral (E)-4-[7]Orthocyclophene, Journal of Organic Chemistry, 10.1021/acs.joc.6b01799, 81, 23, 11587-11593, 2016.12, An efficient synthesis of (E)-4-[7]orthocyclophene (E)-1 via photochemical isomerization of (Z)-1 has been achieved. The key intermediate (Z)-1 was synthesized from commercially available 2-(hydroxymethyl)benzenepropanol (3) in five steps: (i) group-selective Mitsunobu reaction with CH2=CHCH2CH(SO2Ph)2, (ii) oxidation of alcohol, (III) olefination, (iv) RCM, and (v) removal of sulfones in an overall yield of 73%. The photochemical isomerization of (Z)-1 was efficiently performed in the presence of AgNO3-impregnated silica gel (AgNO3/SiO2). The resulting (E)-1 shows dynamic planar chirality at rt. Enantioenriched (E)-1 was prepared by the HPLC separation of enantiomers using a chiral stationary phase, and the absolute stereochemistry was determined by X-ray diffraction analysis of the Pt-coordinated crystalline derivative. The planar chirality of (E)-1 can be converted into the central chirality of carbon; e.g., the oxidation of (R)-(E)-1 using DMDO provided epoxide (8S,9S)-9 in a stereospecific manner. Furthermore, the Lewis acid-promoted reaction of (8S,9S)-9 afforded a unique tricyclic compound (8S,9S)-10 in an excellent yield and in a stereospecific manner.. |
10. |
Kazunobu Igawa, Daisuke Yoshihiro, Yusuke Abe, Katsuhiko Tomooka, Enantioselective Synthesis of Silacyclopentanes, Angew. Chem. Int. Ed., DOI: 10.1002/anie.201511728, 55, 5814-5818, 2016.04, A variety of functionalized silacyclopentanes were synthesized by highly enantioselective β‐eliminations of silacyclopentene oxides followed by stereospecific transformations. The reaction mechanism of the β‐elimination was elucidated by DFT calculations. An in vitro biological assay with an oxy‐functionalized silacyclopentane showed substantial binding to a serotonin receptor protein.. |
11. |
Kazunobu Igawa, Nobumasa Ichikawa, Yusuke Ano, Keisuke Katanoda, Masato Ito, Toshiyuki Akiyama, Katsuhiko Tomooka, Catalytic Enantioselective Synthesis of Planar Chiral Cyclic Amides Based on Pd-catalyzed Asymmetric Allylic Substitution Reaction, J. Am. Chem. Soc., 10.1021/jacs.5b04340, 137, 23, 7294-7297, 2015.06. |
12. |
Kazunobu Igawa, Shouji Miyasaka, Shougo Motomura, Katsuhiko Tomooka, Planar Chiral Dialkoxysilane: Introduction of Inherent Chirality and High Reactivity in Conventional Achiral Alkene, Chem. Eur. J., 10.1002/chem.201402434, 20, 7598-7602, 2014.05. |
13. |
Kazunobu Igawa, Takeshi Kawabata, Runyan Ni, Katsuhiko Tomooka, Synthesis, Structural Analysis, and Reaction of 3-Aza-5-[7]orthocyclophyne, Chem. Lett, 10.1246/cl.130735, 42, 1374-1376, 2013.11. |
14. |
Suguru Yoshida, Kazunobu Igawa, Katsuhiko Tomooka, Nucleophilic Substitution Reaction at the Nitrogen of Arylsulfonamides with Phosphide Anion, J. Am. Chem. Soc., 10.1021/ja309642r, 134, 19358-19361, 2012.11. |
15. |
Kazunobu Igawa, Daisuke Yoshihiro, Nobumasa Ichikawa, Naoto Kokan, Katsuhiko Tomooka, Catalytic Enantioselective Synthesis of Alkenylhydrosilanes, Angew. Chem. Int. Ed., 10.1002/anie.201207361, 51, 12745-12748, 2012.11. |
16. |
Katsuhiko Tomooka, Chisato Iso, Kazuhiro Uehara, Masaki Suzuki, Rie Nishikawa-Shimono, Kazunobu Igawa, Planar-Chiral [7]Orthocyclophanes, Angew. Chem. Int. Ed., 10.1002/anie.201204484, 51, 10355-10358, 2012.09. |
17. |
Kawasaki, Y.; Ishikawa, Y.; Igawa, K.; Tomooka, K., Directing Group-Controlled Hydrosilylation: Regioselective Functionalization of Alkyne, J. Am. Chem. Soc., 10.1021/ja209553f, 133, 20712-20715, 2011.12, アルキンの変換法として重要なヒドロシリル化反応について,従来は困難であった「反応の位置制御」の問題を解決した.具体的には,分子内に配向基を導入することでヒドロシリル化反応を触媒する白金錯体の位置を制御し,その結果としての生成物の位置制御を行うという新手法を開発した.本法により,精密有機合成化学において重要な非対称アルケニルシランの効率的合成が初めて可能となった.. |
18. |
Tomooka, K.; Suzuki, M.; Shimada, M.; Ni, R.; Uehara, K., Stereoselective Multimodal Transformations of Planar Chiral 9-Membered Diallylic Amides, Organic Lett., 10.1021/ol202009x, 13, 18, 4926–4929, 2011.08. |
19. |
Tomooka, K.; Inoue, H.; Igawa, K., Synthesis and Stereochemical Behavior of (E)-Cyclononene Derivatives, Chemistry Letters, 10.1246/cl.2011.591, 40, 6, 591-593, 2011.06. |
20. |
Igawa, K.; Kawasaki, Y; Tomooka, K., Addition-type Oxidation of Silylalkene using Ozone: An Efficient Approach for Acyloin and Its Derivatives, Chemistry Letters, 10.1246/cl.2011.233, 40, 3, 233-235, 2011.02. |
21. |
Tomooka, K.; Ezawa, T.; Inoue, H.; Uehara, K.; Igawa, K., Dynamic Chirality of (E)-5-Cyclononen-1-one and its Enolate, J. Am. Chem. Soc., 10.1021/ja1092375, 2011.01. |
22. |
Tomooka, K.; Shimada, M.; Uehara, K.; Ito, M., A Unique Functional Group Transformation of Planar Chiral Diolefinic Organonitrogen Cycles Utilizing PtCl2(2,4,6-trimethylpyridine) Complexes, Organometallics, 29, 24, 6632–6635, 2010.11. |
23. |
Tomooka, K.; Uehara, K.; Nishikawa, R.; Suzuki, M.; Igawa, K., Enantioselective Synthesis of Planar Chiral Organonitrogen Cycles, J. Am. Chem. Soc., 132, 27, 9232-9233., 2010.06. |
24. |
Igawa K.; Kokan N.; Tomooka K., Asymmetric Synthesis of Chiral Silacarboxylic Acids and Their Ester Derivatives, Angew. Chem. Int. Ed., 49, 4, 728-731., 2010.01. |
25. |
Uehara K.; Tomooka K., Planar Chiral Organosulfur Cycles, Chem. Lett., 38, 11, 1028-1029., 2009.10. |
26. |
Igawa, K.; Takada, J.; Shimono, T.; Tomooka, K., Enantioselective Synthesis of Silanol, J. Am. Chem. Soc., 130, 48, 16132-16133., 2008.12. |
27. |
Tomooka, K.; Suzuki, M.; Uehara, K.; Shimada, M.; Akiyama, T., Novel Synthetic Approach to Nine-Membered Diallylic Amides: Stereochemical Behavior and Utility as Chiral Building Block, Synlett, 16, 2518-2522., 2008.09. |
28. |
Tomooka, K.; Akiyama, T.; Man, P.; Suzuki, M., Asymmetric Synthesis of (-)- and (+)-Kainic acid using a Planar Chiral Amide as a Chiral Building Block, Tetrahedron Letters, 49, 6327-6329., 2008.09. |
29. |
Nakazaki, A.; Usuki, J.; Tomooka, K., Stereoselective 1,4-Phenyl Migration from Silicon to Carbon in α-Siloxy Cyclic Acetal Systems: A Concise Synthesis of 1,2-cis-Phenyl C-Glycoside and Enantioenriched Silanol, Synlett, 13号,2064-2068頁, 2008.07. |
30. |
Igawa, K.; Sakita, K.; Murakami, M.; Tomooka, K., Partial Oxydation of Alkenylsilane with Ozone: A Novel Stereoselective Approach for the Diol- and Triol-derivatives, Synthesis, 10号,1641-1645頁, 2008.05. |
31. |
Tomooka, K.; Sakamaki, J.; Harada, M.; Wada, R., Enantioselective [1,2]-Stevens rearrangement using sugar-derived alkoxides as chiral promoters, Synlett, 5号,683-686頁, 2008.03. |
32. |
Murakami, M.; Sakita, K.; Igawa, K.; Tomooka, K., Stereoselective Oxy-Functionalization of γ-Silyl Allylic Alcohols with Ozone: A Facile Synthesis of Silyl Peroxide and Its Reactions, Organic Letters, 8巻,18号,4023-4026頁, 2006.08. |
33. |
Nakazaki, A.; Nakai, T.; Tomooka, K., Asymmetric Retro-[1,4] Brook Rearrangement and its Stereochemical Course at Silicon, Angew. Chem. Int. Ed., 45巻,14号,2235-2238頁, 2006.03. |
34. |
Tomooka, K.; Suzuki, M.; Shimada, M.; Yanagitsuru, S.-i.; Uehara, K., Planar Chiral Cyclic Amine and Its Derivatives: Synthesis and Stereochemical Behavior, Organic Letters, 8巻,5号,2449-2453頁, 2006.01. |
35. |
Igawa K.; Tomooka, K., γ-Silyl Group Effect in Hydroalumination and Carbolithiation of Propargylic Alcohols, Angew. Chem. Int. Ed., 45巻,2号,232-234頁, 2005.12. |
36. |
Tomooka, K.; Komine, N.; Fujiki, D.; Nakai, T.; Yanagitsuru, S., Planar Chiral Cyclic Ether: Asymmetric Resolution and Chirality Transformation, J. Am. Chem. Soc., 127巻,35号,12182-12183頁, 2005.08. |
37. |
Tomooka, K.; Yamamoto, H.; Nakai, T., Stereoselective Synthesis of Highly Functionalized C-Glycosides based on the Acetal [1,2]- and [1,4]-Wittig Rearrangements, Angew. Chem. Int. Ed., 39巻,24号,4500-4502頁, 2000.12. |
38. |
Tomooka, K.; Kikuchi, M.; Igawa, K.; Suzuki, M.; Keong, P.-h.; Nakai, T., Stereoselective Total Synthesis of Zaragozic Acid A based on an Acetal [1,2]-Wittig Rearrangement, Angew. Chem. Int. Ed., 39巻,24号,4503-4505頁, 2000.12. |
39. |
Tomooka, K.; Nakazaki, A.; Nakai, T., A Novel Aryl Migration from Silicon to Carbon: An Efficient Approach to Asymmetric Synthesis of α-Aryl β-Hydroxy Cyclic Amines and Silanols, J. Am. Chem. Soc., 122巻,2号,40-409頁, 2000.01. |
40. |
Tomooka, K.; Yamamoto, K.; Nakai, T., Enantioselective [1,2]-Wittig Rearrangement using an External Chiral Ligand, Angew. Chem. Int. Ed., 38巻,24号,3741-3743頁, 1999.12. |