Synlett 2016; 27(06): 941-945
DOI: 10.1055/s-0035-1560548
letter
© Georg Thieme Verlag Stuttgart · New York

C 2-Symmetric Chiral Sulfoxide-Mediated Intermolecular Interrupted Pummerer Reaction for Enantioselective Construction of C3a-Substituted Pyrroloindolines

Masanori Tayu
Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo, 204-8588, Japan   eMail: kawasaki@my-pharm.ac.jp
,
Yui Suzuki
Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo, 204-8588, Japan   eMail: kawasaki@my-pharm.ac.jp
,
Kazuhiro Higuchi*
Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo, 204-8588, Japan   eMail: kawasaki@my-pharm.ac.jp
,
Tomomi Kawasaki*
Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo, 204-8588, Japan   eMail: kawasaki@my-pharm.ac.jp
› Institutsangaben
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Publikationsverlauf

Received: 04. Oktober 2015

Accepted after revision: 22. Oktober 2015

Publikationsdatum:
07. Januar 2016 (online)


Abstract

The first example of an enantioselective intermolecular interrupted Pummerer reaction has been developed by the utilization of a C 2-symmetric chiral sulfoxide. The reaction was used for the enantioselective synthesis of C3a-substituted pyrroloindolines in a one-pot procedure starting from tryptamine. The synthetic utility of the reaction was further demonstrated by its application to the highly concise total synthesis of (+)-psychotriasine.

Supporting Information

 
  • References and Notes


    • For nucleophilic additions to carbonyl groups, see:
    • 3a Nakamura S, Takemoto H, Ueno Y, Toru T, Kakumoto T, Hagiwara T. J. Org. Chem. 2000; 65: 469
    • 3b García Ruano JL, Aranda MT, Aguirre JM. Tetrahedron 2004; 60: 5383
    • 3c Colobert F, Obringer M, Solladié G. Eur. J. Org. Chem. 2006; 1455
  • 7 For radical additions, see: Toru T, Watanabe Y, Mase N, Tsusaka M, Hayakawa T, Ueno Y. Pure Appl. Chem. 1996; 68: 711
  • 11 The syntheses of C 2-symmetric sulfoxides 3ac are described in the Supporting Information.
  • 12 The determination of the absolute configuration of 4a is described in the Supporting Information. Tentative absolute configurations of other products were estimated from that of 4a.
  • 13 Synthesis of 4; General Procedure: Acid anhydride (0.20 mmol, 1.0 equiv) was added to a solution of 2 (0.20 mmol, 1.0 equiv) and sulfoxide 3c (26 μL, 0.20 mmol, 1.0 equiv) in EtCN (1.0 mL, 0.20 M) at –78 °C under an argon atmosphere. After stirring for 10 min, DTBP (90 μL, 0.40 mol, 2.0 equiv) was added and the reaction mixture was stirred for a further 10 min. N-Methylindole (25 μL, 0.20 mmol, 1.0 equiv) was added and the reaction mixture was warmed to 0 °C over 10 min with stirring. The reaction mixture was neutralized with saturated aqueous NaHCO3 at 0 °C, and then extracted three times with DCM. The organic layer was washed with brine, dried over MgSO4, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane–EtOAc) to afford the corresponding pyrroloindoline 4.
  • 14 Analytical Data for Compound (–)-4a: The ee was determined by chiral HPLC analysis to be 94% ee {CHIRALPAK IA column; hexane–2-propanol (95:5); Rt  = 19 (+), 27 (–) min}; [α] d 28 −155.7 (c = 0.07, CHCl3). IR (CHCl3): 1692, 1493, 1452 cm–1. 1H NMR (500 MHz, DMSO-d 6, 80 °C): δ = 2.36 (ddd, J = 12.5, 6.3, 3.5 Hz, 1 H), 2.78 (ddd, J = 12.5, 9.0, 9.0 Hz, 1 H), 3.15–3.28 (m, 1 H), 3.50 (s, 3 H), 3.70 (s, 3 H), 3.94 (ddd, J = 10.5, 7.5, 3.0 Hz, 1 H), 4.58 (d, J = 16.2 Hz, 1 H), 4.69 (d, J = 16.2 Hz, 1 H), 5.84 (s, 1 H), 6.45 (d, J = 7.6 Hz, 1 H), 6.57 (dd, J = 7.6, 7.6 Hz, 1 H), 6.83 (dd, J = 7.6, 7.6 Hz, 1 H), 6.93 (d, J = 7.6 Hz, 1 H), 6.97–7.07 (m, 2 H), 7.09 (dd, J = 7.6, 7.6 Hz, 1 H), 7.11 (s, 1 H), 7.16–7.22 (m, 1 H), 7.22–7.28 (m, 2 H), 7.28–7.32 (m, 2 H), 7.34 (d, J = 7.6 Hz, 1 H). 13C NMR (125 MHz, DMSO-d 6, 80 °C): δ = 31.8, 37.6, 45.0, 49.1, 51.6, 55.1, 86.6, 105.7, 109.4, 116.3, 117.0, 118.2, 119.0, 120.8, 123.0, 125.3, 126.2, 126.48, 126.52, 126.6, 127.7, 132.6, 137.4, 138.7, 148.9, 154.6. MS (EI): m/z (%) = 437 (32) [M]+, 405 (22), 350 (17), 349 (100), 335 (22), 258 (20), 257 (41), 91 (10). HRMS (EI): m/z calcd for C28H27N3O2: 437.2103; found: 437.2102.
  • 16 One-pot oxidation was carried out because of the instability of 11 during purification.