PDF herunterladen
Synlett
DOI: 10.1055/a-2551-4541
letter

Chiral Silver Alkoxide Catalyzed Asymmetric Mannich-Type Reaction of Alkenyl Esters with Isatin Imines

Akira Yanagisawa∗
,
Kyonosuke Gomi
,
Ririko Uga
,
Ryusei Suga
This work was supported by MEXT/JSPS KAKENHI (Grant Numbers 16K05766 and 19K05450). We gratefully acknowledge the financial support from Nippon Chemical Industrial Co., Ltd.
› Weitere Informationen
    Lizenzen und Reprints Alle Artikel dieser Rubrik


Abstract

A catalytic enantioselective Mannich-type reaction of alkenyl esters with isatin imines was achieved by using a Tol-BINAP·AgSbF6 complex as the chiral precatalyst and N,N-diisopropylethylamine as the base precatalyst in the presence of methanol. Optically active 3-alkylated 3-amino-2-oxindoles having up to 98% ee were diastereoselectively obtained in moderate to high yields not only from acyclic alkenyl esters but also from cyclic esters through the in situ generated chiral silver enolates.

Key words

alkenyl ester - asymmetric catalysis - isatin imine - Mannich-type reaction - silver

Supporting Information

    Supporting information for this article is available online at https://doi.org/10.1055/a-2551-4541.
  • Supporting Information


Publikationsverlauf

Eingereicht: 26. Dezember 2024

Angenommen nach Revision: 05. März 2025

Accepted Manuscript online:
05. März 2025

Artikel online veröffentlicht:
10. April 2025

© 2025. Thieme. All rights reserved

Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

 

  • References and Notes

  • 1 Kitamura H, Kato A, Esaki T. Eur. J. Pharmacol. 2001; 418: 225
    PubMedSuche in Google Scholar
  • 2 Hara N, Nakamura S, Sano M, Tamura R, Funahashi Y, Shibata N. Chem. Eur. J. 2012; 18: 9276
    CrossrefPubMedSuche in Google Scholar
  • 8 Yanagisawa A, Lin Y, Miyake R, Yoshida K. Org. Lett. 2014; 16: 86
    PubMedSuche in Google Scholar

      • In our previous study on the chiral silver(I)-catalyzed asymmetric allylation of aldehydes, we showed that a considerable amount of an inert 2:1 complex of BINAP/silver(I) salt was formed, accompanied by a reactive 1:1 complex, when BINAP was added to an equimolar amount of the silver salt in MeOH. In the reaction, a 0.6:1 mixture of BINAP/silver(I) salt was found to produce the desired 1:1 complex without the formation of the 2:1 complex:
    • 10a Yanagisawa A, Kageyama H, Nakatsuka Y, Asakawa K, Matsumoto Y, Yamamoto H. Angew. Chem. Int. Ed. 1999; 38: 3701
      CrossrefPubMedSuche in Google Scholar
    • 10b Yanagisawa A, Nakatsuka Y, Asakawa K, Kageyama H, Yamamoto H. Synlett 2001; 69
    • 10c Yanagisawa A, Nakatsuka Y, Asakawa K, Wadamoto M, Kageyama H, Yamamoto H. Bull. Chem. Soc. Jpn. 2001; 74: 1477
      CrossrefSuche in Google Scholar
  • 11 Asymmetric Mannich-Type Reaction Catalyzed by (R)-Tol-BINAP·AgSbF6 and (i-Pr)2NEt; Typical Procedure: Synthesis of 1-Benzyl-3-((4-bromophenyl)amino)-3-(1-oxo-1-phenylpropan-2-yl)indolin-2-one (3aa) A mixture of AgSbF6 (27.5 mg, 0.08 mmol), (R)-Tol-BINAP (27.2 mg, 0.04 mmol), and isatin imine 2a (195.6 mg, 0.5 mmol) was dissolved in anhydrous THF (6 mL) under an argon atmosphere and with direct light excluded, and stirred at room temperature for 20 min. To the resulting solution were added CH3OH (40.6 μL, 1.0 mmol) and (i-Pr)2NEt (17 μL, 0.10 mmol) successively at –40 °C. The mixture was stirred at that temperature for 5 min, then alkenyl trifluoroacetate 1a (142.0 μL, 0.75 mmol) was added dropwise to the resulting solution at –40 °C. After stirring for 1.5 h at that temperature, the mixture was treated with MeOH (3 mL). The mixture was then filtered through a glass filter funnel filled with Celite®, washed with EtOAc, and the combined filtrate and washes were concentrated in vacuo. The residual crude product was purified by column chromatography on silica gel to give the corresponding β-amino ketone 3aa (255.7 mg, 97% yield). The diastereomeric ratio was determined to be 92:8 by 1H NMR analysis. The enantiomeric ratio of the major isomer was determined to be 86% ee by HPLC analysis using a chiral column [Daicel Chiralpak AD-3, hexane–i-PrOH (4:1), flow rate = 1.0 mL/min] t 1 = 17.9 min (minor), t 2 = 117.6 min (major). The enantiomeric ratio of the minor isomer was determined to be 4% ee by HPLC analysis using a chiral column [Daicel Chiralpak AD-3, hexane–i-PrOH (4:1), flow rate = 1.0 mL/min] t 1 = 35.7 min (major), t 2 = 64.0 min (minor). [α]21.4 D +44.2 (c 1.0, CHCl3, 86% ee); mp 48–53 °C. 1H NMR (392 MHz, CDCl3): δ = 7.90 (d, J = 7.1 Hz, 2 H), 7.53–7.62 (m, 2 H), 7.46 (t, J = 8.2 Hz, 2 H), 7.26–7.28 (m, 4 H), 7.14 (m, 2 H), 7.06 (t, J = 7.9 Hz, 1 H), 6.98 (d, J = 8.6 Hz, 2 H), 6.84 (d, J = 8.6 Hz, 1 H), 6.13 (dt, J = 9.0, 2.5 Hz, 2 H), 5.59 (s, 1 H), 4.94 (d, J = 15.3 Hz, 1 H), 4.77 (d, J = 15.7 Hz, 1 H), 3.93 (q, J = 7.4 Hz, 1 H), 1.34 (d, J = 7.0 Hz, 3 H). 13C NMR (99 MHz, CDCl3): δ = 202.5, 176.8, 144.3, 142.4, 137.3, 135.5, 133.5, 131.6 (2C), 129.6, 128.8 (2C), 128.7 (2C), 128.2 (2C), 127.80, 127.75 (2C), 127.6, 126.2, 122.9, 118.9 (2C), 112.2, 109.7, 67.5, 45.1, 44.1, 13.0. IR (neat): 3341, 1715, 1593, 1486, 1465, 1343, 1259, 1211, 1173, 1075, 1001, 974 cm–1. MS (ESI): m/z [M]+ calcd for [C30H25O2N2Br]+: 524.1094; found: 524.1084.
  • 12 The use of a small amount of MeOH decreased the rate of methanolysis of silver amide 5, resulting low yield of the desired product 3, while an excess amount of MeOH accelerated protonation of the chiral silver enolate 4 and reduced the yield of 3.

      • Two examples of the synthesis of achiral silver alkoxides have been reported, see:
    • 13a Edworthy IS, Rodden M, Mungur SA, Davis KM, Blake AJ, Wilson C, Schröder M, Arnold PL. J. Organomet. Chem. 2005; 690: 5710
      Suche in Google Scholar
    • 13b Reisinger A, Himmel D, Krossing I. Angew. Chem. Int. Ed. 2006; 45: 6997
      CrossrefPubMedSuche in Google Scholar
  • 14 The relative and absolute stereochemistry of the Mannich products has not yet been determined.