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Tanaka D, Konishi A, Yasuda M. Synthesis and Catalytic Activity of Atrane-type Hard and Soft Lewis Superacids with a Silyl, Germyl, or Stannyl Cationic Center. Chem Asian J 2021; 16:3118-3123. [PMID: 34487429 DOI: 10.1002/asia.202100873] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/15/2021] [Indexed: 11/07/2022]
Abstract
The synthesis and isolation of atrane-type molecules 1E+ (E=Si, Ge, or Sn) having a cationic group 14 elemental center are reported. The cations 1E+ act as hard and soft Lewis superacids, which readily interact with various hard and soft Lewis basic substrates. The rigid atrane framework stabilizes the localized positive charge on the elemental center and assists the formation of the well-defined highly coordinated states of 1E+ . The cations were applied to the hydrodefluorination, Friedel-Crafts reaction, alkyne cyclization, and carbonyl reduction as Lewis acid catalysts. Most notably, [1Si][ClO4 ] exhibits unique chemoselectivity that depends on a solvent in the competitive reaction of silyl enol ether with a mixture of benzaldehyde dimethyl acetal and benzaldehyde. Our findings indicate the potential of hard and soft Lewis superacids in organic synthesis.
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Affiliation(s)
- Daiki Tanaka
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Minami Y, Nishida K, Konishi A, Yasuda M. Characterization of Highly Coordinated Allylgermanes: Pivotal Players for Enhanced Nucleophilicity and Stereoselectivity. Chem Asian J 2020; 15:1852-1857. [PMID: 32274892 DOI: 10.1002/asia.202000392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/08/2020] [Indexed: 01/26/2023]
Abstract
Allylgermanes with a 4-, 5-, and 6-coordinated germanium center were characterized by X-ray crystallography. Cationic 6-coordinated group 14 allylmetals, which were hitherto assumed to be a transition-state structure of allylations, were successfully isolated. Forming high coordination states significantly enhanced the reactivity of the allylgermanes. In contrast to the 4-coordinated allylgermanes with low reactivity, the highly coordinated species readily reacted with several aldehydes. Furthermore, the high coordination states exerted a significant effect on the E/Z selectivity of allylation depending on external additives. The coordination structure had a dramatic influence on the electronic and steric environments around the Ge center, enabling the geometrically controlled allylation of aldehydes.
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Affiliation(s)
- Yohei Minami
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kento Nishida
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Minami Y, Konishi A, Yasuda M. Synthesis of α-Alkenyl α,β-Unsaturated Ketones via Dehydrogermylation of Oxagermacycles with Regeneration of the Germanium(II) Species. Org Lett 2019; 21:9818-9823. [PMID: 31682128 DOI: 10.1021/acs.orglett.9b03454] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of α-alkenyl α,β-unsaturated ketones using germanium(II) salts is reported. Oxagermacycles derived from α,β-unsaturated ketones with germanium(II) salts and aldehydes can be transformed into α-alkenyl α,β-unsaturated ketones. Ammonium salts promoted the elimination of Ge(II) species to afford the two classes of α-alkenyl α,β-unsaturated ketones in good yields. The α-alkenyl α,β-unsaturated ketones are precursors for multisubstituted heterocycles.
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Minami Y, Konishi A, Yasuda M. Stereocontrolled Synthesis of Triols Containing Four Asymmetric Centers: Application of C, O-Chelated Germyl Enolates to a Diastereoselective Aldol Reaction. Org Lett 2018; 20:4148-4152. [PMID: 29938514 DOI: 10.1021/acs.orglett.8b01778] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The treatment of α,β-unsaturated ketones with divalent germanium salts cleanly generated C, O-chelated germyl enolates. The aldol reactions of the chelated enolates with the aldehydes achieved a high diastereoselectivity in the construction of the five-membered aldol adducts. Furthermore, the subsequent transformation of the Ge-C bond in the aldol adduct enabled the stereocontrolled synthesis of triols bearing four asymmetric centers.
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Affiliation(s)
- Yohei Minami
- Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan
| | - Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan.,Center for Atomic and Molecular Technologies, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering , Osaka University , 2-1 Yamadaoka, Suita , Osaka 565-0871 , Japan
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