Synlett 2011(4): 469-472  
DOI: 10.1055/s-0030-1259326
CLUSTER
© Georg Thieme Verlag Stuttgart ˙ New York

One-Pot Organocatalytic Asymmetric Synthesis of 1H-Pyrrolo[1,2a]indol-3(2H)-ones via a Michael-Hemiaminalization-Oxidation Sequence

Dieter Enders*, Chuan Wang, Xuena Yang, Gerhard Raabe
Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
Fax: +49(241)8092127; e-Mail: enders@rwth-aachen.de;
Further Information

Publication History

Received 2 November 2010
Publication Date:
19 January 2011 (online)

Abstract

An efficient one-pot organocatalytic asymmetric synthesis of 1,2-cis-disubstituted 1H-pyrrolo[1,2a]indol-3(2H)-ones in moderate to good overall yields (49-68%) is presented. The ­Michael-hemiaminalization-oxidation sequence occurs with very high asymmetric induction and, after purification, virtually stereo­isomerically pure products were obtained (>98% de, >99% ee).

    References and Notes

  • For recent reviews on organocatalysis, see:
  • 1a Berkessel A. Gröger H. Asymmetric Organocatalysis   Wiley-VCH; Weinheim: 2005. 
  • 1b Dalko PI. Enantioselective Organocatalysis   Wiley-VCH; Weinheim: 2007. 
  • 1c Special issue on organocatalysis: Chem. Rev.  2007,  107:  5413 ; guest editor B. List
  • 1d Pellissier H. Tetrahedron  2007,  63:  9267 
  • 1e De Figueiredo RM. Christmann M. Eur. J. Org. Chem.  2007,  2575 
  • 1f Enders D. Grondal C. Hüttl MRM. Angew. Chem. Int. Ed.  2007,  46:  1570 
  • 1g Dondoni A. Massi A. Angew. Chem. Int. Ed.  2008,  47:  4638 
  • 1h Enders D. Narine AA. J. Org. Chem.  2008,  73:  7857 
  • 1i Melchiorre P. Marigo M. Carlone A. Bartoli G. Angew. Chem. Int. Ed.  2008,  47:  6138 
  • 1j Jørgensen KA. Bertelsen S. Chem. Soc. Rev.  2009,  38:  2178 
  • 1k Bella M. Gasperi T. Synthesis  2009,  1583 
  • 1l Grondal C. Jeanty M. Enders D. Nat. Chem.  2010,  2:  167 
  • For a general review on asymmetric Michael additions to nitroalkenes, see:
  • 2a Berner OM. Tedeschi L. Enders D. Eur. J. Org. Chem.  2002,  1877 
  • For recent reviews on organocatalyzed Michael-additions, see:
  • 2b Tsogoeva SB. Eur. J. Org. Chem.  2007,  1701: 
  • 2c Sulzer-Mossé S. Alexakis A. Chem. Commun.  2007,  43:  3123 
  • 2d Vicario JL. Badía D. Carrillo L. Synthesis  2007,  2065 
  • 2e Almaºi D. Alonso DA. Nájera C. Tetrahedron: Asymmetry  2007,  18:  299 
  • 2f Enders D. Wang C. Liebich JX. Chem. Eur. J.  2009,  15:  11058 
  • For first reports on amine-catalyzed asymmetric Michael additions to nitroalkenes via enamine intermediates, see:
  • 3a List B. Pojarliev P. Martin HJ. Org. Lett.  2001,  3:  2423 
  • 3b Sakthivel K. Notz W. Bui T. Barbas CF. J. Am. Chem. Soc.  2001,  123:  5260 
  • 3c Betancort JM. Barbas CF. Org. Lett.  2001,  3:  3737 
  • 3d Betancort JM. Sakthivel K. Thayumanavan R. Barbas CF. Tetrahedron Lett.  2001,  42:  4441 
  • 3e Enders D. Seki A. Synlett  2002,  26 
  • For selected examples of organocatalytic domino or tandem reactions involving Michael additions to nitroalkenes via enamine intermediates, see:
  • 4a Enders D. Hüttl MRM. Grondal C. Raabe G. Nature (London)  2006,  441:  861 
  • 4b Enders D. Hüttl MRM. Runsink J. Raabe G. Wendt B. Angew. Chem. Int. Ed.  2007,  46:  467 
  • 4c Hayashi Y. Okano T. Aratake S. Hazelard D. Angew. Chem. Int. Ed.  2007,  46:  4922 
  • 4d Enders D. Hüttl MRM. Raabe G. Bats JW. Adv. Synth. Catal.  2008,  350:  267 
  • 4e Enders D. Wang C. Bats JW. Angew. Chem. Int. Ed.  2008,  47:  7539 
  • 4f Cao C.-L. Zhou Y.-Y. Zhou J. Sun X.-L. Tang Y. Li Y.-X. Li G.-Y. Sun J. Chem. Eur. J.  2009,  15:  11384 
  • 4g Zhu D. Lu M. Dai L. Zhong G. Angew. Chem. Int. Ed.  2009,  48:  6089 
  • 4h Wu L.-Y. Bencivenni G. Mancinelli M. Mazzanti A. Bartoli G. Melchiorre P. Angew. Chem. Int. Ed.  2009,  48:  7196 
  • 4i Belot S. Vogt KA. Besnard C. Krause N. Alexakis A. Angew. Chem. Int. Ed.  2009,  48:  8923 
  • 4j Enders D. Krüll R. Bettray W. Synthesis  2010,  567 
  • 4k Enders D. Wang C. Mukanova M. Greb A. Chem. Commun.  2010,  46:  2447 
  • 5a Enders D. Wang C. Greb A. Adv. Synth. Catal.  2010,  352:  987 
  • 5b Enders D. Wang C. Yang X. Raabe G. Adv. Synth. Catal.  2010,  352:  2869 
  • 6a Mothes K. Schütte HR. Luckner M. Biochemistry of Alkaloids   Verlag Chemie; Weinheim: 1985. 
  • 6b Southon JW. Buckingham J. Dictionary of Alkaloids   Chapmann and Hall; London: 1988. 
  • 6c Sundberg RJ. Indoles   Academic Press; San Diego: 1996. 
  • For selected examples of organocatalytic domino or one-pot reactions involving indoles as a component, see:
  • 7a Austin J.-F. Kim S.-G. Sinz CJ. Xiao W.-J. MacMillan DWC. Proc. Natl. Acad. Sci. U.S.A.  2004,  101:  5482 
  • 7b Enders D. Narine AA. Toulgoat F. Bisshops T. Angew. Chem. Int. Ed.  2008,  47:  5661 
  • 7c Franzén J. Fisher A. Angew. Chem. Int. Ed.  2009,  48:  787 
  • 7d Enders D. Wang C. Raabe G. Synthesis  2009,  4119 
  • 7e Hong L. Sun W. Liu C. Wang L. Wang R. Chem. Eur. J.  2010,  15:  440 
  • For selected examples of organocatalytic domino reactions involving hemiacetalization, acetalization, or hemi-aminalization steps, see ref. 5b and:
  • 8a Andrey O. Vidonne A. Alexakis A. Tetrahedron Lett.  2003,  44:  7901 
  • 8b Ibrahem I. Rios R. Veseley J. Zhao G.-L. Córdova A. Chem. Commun.  2007,  849 
  • 8c Rueping M. Sugiono E. Merino E. Angew. Chem. Int. Ed.  2008,  47:  3046 
  • 8d Franke T. Richter B. Jørgensen KA. Chem. Eur. J.  2008,  14:  6317 
  • 8e Hayashi Y. Gotoh H. Masui R. Ishikawa H. Angew. Chem. Int. Ed.  2008,  47:  4012 
  • 8f Han B. Li J.-L. Ma C. Zhang S.-J. Chen Y.-C. Angew. Chem. Int. Ed.  2008,  47:  9971 
  • 8g Gotoh H. Okamura D. Ishikawa H. Hayashi Y. Org. Lett.  2009,  11:  4056 
  • 8h Bo H. He Z.-Q. Li J.-L. Li R. Jiang K. Liu T.-J. Chen Y.-C. Angew. Chem. Int. Ed.  2009,  48:  5474 
  • 8i Reyes E. Talavera G. Vicario JL. Badía D. Carrillo L. Angew. Chem. Int. Ed.  2009,  48:  5701 
  • 8j Wang Y. Yu D.-F. Liu Y.-Z. Wei H. Luo Y.-C. Dixon DJ. Xu P.-F. Chem. Eur. J.  2010,  16:  3922 
  • 8k Urushima T. Sakamoto D. Ishikawa H. Hayashi Y. Org. Lett.  2010,  12:  4558 
  • For selected examples of the synthesis of 1H-pyrrolo-[1,2a]indol-3(2H)-ones, see:
  • 9a Crenshaw MD. Zimmer H. J. Heterocycl. Chem.  1984,  21:  623 
  • 9b Vice SF. Friesen RW. Dmitrienko GI. Tetrahedron Lett.  1985,  26:  165 
  • 9c Flitsch W. Langer W. Liebigs Ann. Chem.  1988,  391 
  • 9d Liu J. Shen M. Zhang Y. Li G. Khodabocus A. Rodriguez S. Bo Q. Farina V. Senanayake CH. Lu BZ. Org. Lett.  2006,  8:  3573 
  • 9e Liu J. Zhang Y. Li G. Roschangar F. Farina V. Senanayake CH. Lu BZ. Adv. Synth. Catal.  2010,  352:  2667 
  • For reviews on diphenylprolinol TMS-ether catalysis, see:
  • 10a Palomo C. Mielgo A. Angew. Chem. Int. Ed.  2006,  45:  7876 
  • 10b Mielgo A. Palomo C. Chem. Asian J.  2008,  922 
  • 11a Hayashi Y. Gotoh H. Hayashi T. Shoji M. Angew. Chem. Int. Ed.  2005,  44:  4212 
  • 11b Zhu S. Yu S. Ma D. Angew. Chem. Int. Ed.  2008,  47:  545 
  • 13 Flack HD. Acta Crystallogr., Sect. A: Found. Crystallogr.  1983,  39:  876 
12

CCDC-798847 (6f) contains the supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

14

General Procedure
To a solution of aldehydes 1 (3.0 mmol, 3.0 equiv), (E)-2-(2-nitrovinyl)-1H-indoles 2 (1.0 mmol, 1.0 equiv), and AcOH (0.20 mmol, 20 mol%) in CH2Cl2 (4.0 mL) was added (R)-diphenylprolinol TMS-ether [(R)-3] (0.15 mmol, 15 mol%). After stirring for 1 d, the reaction mixture was treated with pyridinium chloromate (2.0 mmol, 2.0 equiv) and stirred at r.t. for 1 d. The crude product was purified by flash chromatography on silica gel (pentane-Et2O mixture) affording the corresponding 1H-pyrrolo[1,2a]indol-3
(2H)-ones 6 as a solid or sirup. (1 S ,2 S )-2-Butyl-7-chloro-1-(nitromethyl)-1 H -pyrrolo[1,2- a ]indol-3 (2 H )-one (6f) Isolated as a yellow solid (186 mg, 58%). The ee (>99%) was determined by HPLC on a chiral stationary phase [Chiralcel OD, n-heptane-EtOH (9:1), 1.0 mL/min), t R = 11.52 min (major), 13.16 min (minor, based on the racemic mixture)]; mp 108 ˚C; [α]D ²0 = 77.2 (c 0.32, CHCl3). IR (KBr): 3293, 3196, 2955, 2924, 2867, 2160, 2064, 1725, 1662, 1598, 1582, 1554, 1498, 1446, 1391, 1360, 1317, 1264, 1201, 1167, 1146, 1055, 968, 946, 914, 893, 868, 810, 777, 754, 712, 693, 677, 655 cm. ¹H NMR (300 MHz, CDCl3): δ = 0.96 (t, J = 7.2 Hz, 3 H), 1.26-1.66 (m, 5 H), 1.88-2.00 (m, 1 H), 3.36-3.44 (m, 1 H), 4.32-4.40 (m, 1 H), 4.48-4.56 (m, 1 H), 4.71-4.77 (m, 1 H), 6.29 (s, 1 H), 7.25-7.29 (m, 1 H), 7.48 (d, J = 2.8 Hz, 1 H), 7.93 (d, J = 8.7 Hz, 1 H) ppm. ¹³C NMR (75 MHz, CDCl3): δ = 13.8, 22.6, 26.1, 29.7, 34.4, 48.5, 74.8, 101.8, 114.6, 120.9, 124.6, 128.8, 130.0, 135.5, 142.0, 171.1 ppm. MS (EI, 70 eV): m/z (%) = 320 (33) [M+], 273 (29), 219 (36), 217 (100). ESI-HRMS: m/z calcd for C16H17O3N2 ³5Cl: 320.0922; found: 320.0923.