Gold(I)-Catalyzed Hydroamination as a General Approach toward the Synthesis of Substituted Hydroisoquinolines: Remarkable Acceleration by Ethanol

Taro Enomoto; Shingo Obika; Yoshizumi Yasui; Yoshiji Takemoto

doi:10.1055/s-2008-1077879

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Synlett 2008(11): 1647-1650
DOI: 10.1055/s-2008-1077879

LETTER

Gold(I)-Catalyzed Hydroamination as a General Approach toward the Synthesis of Substituted Hydroisoquinolines: Remarkable Acceleration by Ethanol

Taro Enomoto, Shingo Obika, Yoshizumi Yasui, Yoshiji Takemoto*
Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan
Fax: +81(75)7534569; e-Mail: takemoto@pharm.kyoto-u.ac.jp;

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Publication History

Received 13 March 2008
Publication Date:
11 June 2008 (online)

Abstract
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Abstract

Construction of 1,2-dihydroisoquinolines and 1-alkylidenyl-1,2,3,4-tetrahydroisoquinolines through cationic gold(I) complex catalyzed hydroamination of the corresponding alkynyl carbamates has been demonstrated. In the presence of EtOH, the reaction proceeded smoothly at room temperature with low catalyst loading (1-3 mol%).

Key words

hydroamination - isoquinolines - catalysis - heterocycles - cyclizations

References and Notes

1a Scott JD. Williams RM. Chem. Rev. 2002, 102: 1669

Crossref Google Scholar
1b Chrzanowska M. Rozwadowska MD. Chem. Rev. 2004, 104: 3341

Crossref Google Scholar
2a Yanada R. Obika S. Kono H. Takemoto Y. Angew. Chem. Int. Ed. 2006, 45: 3822

Crossref PubMed Google Scholar
2b Obika S. Kono H. Yasui Y. Yanada R. Takemoto Y. J. Org. Chem. 2007, 72: 4462

Crossref PubMed Google Scholar
For related addition-cyclizations, see:
3a Ohtaka M. Nakamura H. Yamamoto Y. Tetrahedron Lett. 2004, 45: 7339

Crossref Google Scholar
3b Asao NS. Yudha S. Nogami T. Yamamoto Y. Angew. Chem. Int. Ed. 2005, 44: 5526

Crossref Google Scholar
3c Gao K. Wu J. J. Org. Chem. 2007, 72: 8611

Crossref Google Scholar
3d Ding Q. Wu J. Org. Lett. 2007, 9: 4959

Crossref Google Scholar
3e Su S. Porco JA. Org. Lett. 2007, 9: 4983

Crossref Google Scholar
5 For examples of 1-alkylidenyl-1,2,3,4-tetrahydroiso-quinoline syntheses, see: Ivanov I. Nikolova S. Statkova-Abeghe S. Angelov P. Heterocycles 2006, 68: 387 ; and references cited therein

Google Scholar
For a review, see:
6a Matsubara R. Kobayashi S. Acc. Chem. Res. 2008, 41: 292

Crossref Google Scholar
For selected recent examples, see:
6b Cossey KN. Funk RL. J. Am. Chem. Soc. 2004, 126: 12216

Crossref Google Scholar
6c Matsubara R. Kobayashi S. Angew. Chem. Int. Ed. 2006, 45: 7993

Crossref Google Scholar
6d Terada M. Sorimachi K. J. Am. Chem. Soc. 2007, 129: 292

Crossref Google Scholar
6e Harrison TJ. Patrick BO. Dake GR. Org. Lett. 2007, 9: 367

Crossref Google Scholar
To the best of our knowledge, there are only two reports describing six-membered-ring formation through hydro-amination of alkynyl amides or carbamates at room temperature:
7a Sashida H. Kawamukai A. Synthesis 1999, 1145

Crossref Google Scholar
7b Ritter S. Horino Y. Lex J. Schmalz H.-G. Synlett 2006, 3309

Crossref Google Scholar
For a 6-endo hydroalkoxylation, see:
7c Hashmi ASK. Schäfer S. Wölfle M. Gil CD. Fischer P. Laguna A. Blanco MC. Gimeno MC. Angew. Chem. Int. Ed. 2007, 46: 6184

Crossref Google Scholar
8a Alonso F. Beletskaya IP. Yus M. Chem. Rev. 2004, 104: 3079

Google Scholar
8b Severin R. Doye S. Chem. Soc. Rev. 2007, 36: 1407

Google Scholar
9a Kadzimirsz D. Hildebrandt D. Merz K. Dyker G. Chem. Commun. 2006, 661

Crossref Google Scholar
9b Yu Y. Stephenson GA. Mitchell D. Tetrahedron Lett. 2006, 47: 3811

Crossref Google Scholar
9c Ding Q. Ye Y. Fan R. Wu J. J. Org. Chem. 2007, 72: 5439

Crossref Google Scholar
9d
See also ref 3c.

Crossref
12a Teles JH. Brode S. Chabanas M. Angew. Chem. Int. Ed. 1998, 37: 1415

Crossref Google Scholar
12b Mézailles N. Ricard L. Gagosz F. Org. Lett. 2005, 7: 4133

Crossref Google Scholar
For recent reviews of gold-catalyzed reactions, see:
13a Gorin DJ. Toste FD. Nature (London) 2007, 446: 395

Google Scholar
13b Fürstner A. Davies PW. Angew. Chem. Int. Ed. 2007, 46: 3410

Google Scholar
13c Hashmi ASK. Chem. Rev. 2007, 107: 3180

Google Scholar
13d Jiménez-Núnez E. Echavarren AM. Chem. Commun. 2007, 333

Google Scholar
13e Recently, we reported that the catalyst, generated from AuCl(PPh₃) and AgNTf₂, promotes the 6-endo cyclization of N-Boc-propargylamines. See: Miyabe H. Sami Y. Naito T. Takemoto Y. Heterocycles 2007, 73: 187

Google Scholar
For recent examples of gold-catalyzed hydroaminations, see:
14a Zhang J. Yang C.-G. He C. J. Am. Chem. Soc. 2006, 128: 1798

Crossref Google Scholar
14b Hashmi ASK. Rudolph M. Schymura S. Visus J. Frey W. Eur. J. Org. Chem. 2006, 4905

Crossref Google Scholar
14c Liu X.-Y. Ding P. Huang J.-S. Che C.-M. Org. Lett. 2007, 9: 2645

Crossref Google Scholar
14d Ritter S. Hackelöer K. Schmalz H.-G. Heterocycles 2007, 74: 731

Crossref Google Scholar
14e
See also ref 9a.

Crossref Google Scholar
15a Mizushima E. Sato K. Hayashi T. Tanaka M. Angew. Chem. Int. Ed. 2002, 41: 4563

Crossref PubMed Google Scholar
15b Mizushima E. Hayashi T. Tanaka M. Org. Lett. 2003, 5: 3349

Crossref PubMed Google Scholar
For examples, see:
16a Piera J. Krumlinde P. Strübing D. Bäckvall J.-E. Org. Lett. 2007, 9: 2235

Google Scholar
16b Watanabe T. Oishi S. Fujii N. Ohno H. Org. Lett. 2007, 9: 4821

Google Scholar
16c
Also see ref 12a.

Google Scholar
17 Similar high-field shifts have been observed often in related systems. For example, see: Cava MP. Mitchell MJ. Havlicek SC. Lindert A. Spangler RJ. J. Org. Chem. 1970, 35: 175

Crossref Google Scholar
18 For example, see: Kitamura M. Hsiao Y. Ohta M. Tsukamoto M. Ohta T. Takaya H. Noyori R. J. Org. Chem. 1994, 59: 297

Crossref Google Scholar

4

For examples of 1,2-dihydroisoquinoline syntheses, see references cited in ref 2.

10

The corresponding 5-exo cyclized products, namely isoindoles, were not detected in this work, presumably due to their instability.

11

Structure of 2a was fully confirmed by spectroscopy and by its conversion into known 3-phenylisoquinoline; from 1a,
3-phenylisoquinoline was obtained in 70% yield after cleavage of Boc group (TFA, CH₂Cl₂, r.t., 30 min) followed by oxidation (I₂, KOAc, EtOH, reflux, 1 h).

19

Typical Procedure for the Gold(I)-Catalyzed Hydroamination: To a solution of 1a (309 mg, 1.00 mmol) in DCE (2 mL) were added EtOH (231 mg, 293 µL, 5.02 mmol) and a suspension of AuCl(PPh₃) (4.9 mg, 0.0099 mmol) and AgNTf₂ (3.8 mg, 0.0098 mmol) in DCE (1 mL) at r.t. After stirring for 2 h, sat. aq NaHCO₃ was added and the product was extracted with CHCl₃ (3 × 10 mL). The combined organic extracts were washed with brine, dried over Na₂SO₄, filtered, and concentrated. The residue was purified by silica gel column chromatography (hexane-EtOAc, 25:1) to afford 2a (256 mg, 83%) as colorless crystals: R _f 0.70 (hexane-EtOAc, 3:1); mp 105-106 °C. ¹H NMR (500 MHz, CDCl₃, TMS): δ = 7.48 (d, J = 7.3 Hz, 2 H), 7.36 (dd, J ₁ = 7.1 Hz, J ₂ = 7.3 Hz, 2 H), 7.30 (t, J = 7.1 Hz, 1 H), 7.18-7.27 (m, 4 H), 6.42 (s, 1 H), 4.89 (s, 2 H), 1.05 (s, 9 H). ¹³C NMR (126 MHz, CDCl₃): δ = 153.0, 140.6, 139.0, 132.7, 132.0, 128.1, 127.7, 127.5, 127.2, 126.3, 125.1, 125.0, 115.2, 81.0, 47.5, 27.6. IR (CHCl₃): 1693
cm^-1. MS (FAB): m/z = 307 [M⁺]. Anal. Calcd for C₂₀H₂₁NO₂: C, 78.15; H, 6.89; 4.56. Found: C, 78.23; H, 7.07; N, 4.48.
Compound 2e: colorless crystals; R _f 0.55 (hexane-EtOAc, 6:1); mp 168-169 °C. ¹H NMR (500 MHz, CDCl₃, TMS): δ = 7.16-7.26 (m, 4 H), 7.09 (s, 2 H), 6.94 (s, 1 H), 6.41 (s, 1 H), 4.87 (s, 2 H), 2.33 (s, 6 H), 1.06 (s, 9 H). ¹³C NMR (126 MHz, CDCl₃): δ = 153.0, 140.8, 138.7, 137.5, 132.7, 131.9, 129.3, 127.5, 127.0, 125.0, 124.9, 124.1, 114.6, 80.8, 47.5, 27.6, 21.2. IR (CHCl₃): 1691 cm^-1. MS (FAB): m/z = 335 [M⁺]. Anal. Calcd for C₂₂H₂₅NO₂: C, 78.77; H, 7.51; N, 4.18. Found: C, 78.66; H, 7.50; N, 4.23.
Compound 2h: white powder; R _f 0.50 (hexane-EtOAc, 1:1); mp 115-116 °C. ¹H NMR (500 MHz, CDCl₃, TMS): δ = 7.46 (d, J = 8.2 Hz, 2 H), 7.34 (d, J = 8.2 Hz, 2 H), 7.15-7.26 (m, 4 H), 6.42 (s, 1 H), 4.85 (s, 2 H), 4.68 (s, 2 H), 2.58 (s, 1 H), 1.06 (s, 9 H). ¹³C NMR (126 MHz, CDCl₃): δ = 152.9, 140.6, 140.2, 137.9, 132.5, 131.8, 127.5, 127.2, 126.6, 126.2, 125.0, 124.9, 115.2, 81.0, 64.7, 47.4, 27.6.
IR (CHCl₃): 3606, 1693 cm^-1. MS (FAB): m/z = 337 [M⁺]. Anal. Calcd for C₂₁H₂₃NO₃: C, 74.75; H, 6.87; N, 4.15. Found: C, 74.47; H, 6.87; N, 3.88.
Compound 4a: colorless needles: R _f 0.38 (hexane-EtOAc, 2:1); mp 164-165 °C. ¹H NMR (500 MHz, CDCl₃, TMS): δ = 7.47 (d, J = 7.6 Hz, 2 H), 7.32 (dd, J ₁ = J ₂ = 7.6 Hz, 2 H), 7.21 (s, 1 H), 7.19 (t, J = 7.6 Hz, 1 H), 6.74 (s, 1 H), 6.61 (s, 1 H), 4.60 (br, 1 H), 3.97 (s, 3 H), 3.89 (s, 3 H), 3.27 (br, 1 H), 3.13 (br, 1 H), 2.66 (br, 1 H), 1.02 (s, 9 H). ¹³C NMR (126 MHz, CDCl₃): δ = 153.3, 149.3, 147.7, 137.2, 134.0, 128.4, 128.3, 128.0, 126.8, 125.4, 117.6, 111.7, 106.4, 80.3, 56.2, 55.9, 43.0, 28.5, 27.7. IR (CHCl₃): 1682 cm^-1.
MS (FAB): m/z = 381 [M⁺]. Anal. Calcd for C₂₃H₂₇NO₄: C, 72.42; H, 7.13; N, 3.67. Found: C, 72.38; H, 7.08; N, 3.47.
Compound 4c: colorless crystals; R _f 0.38 (hexane-EtOAc, 2:1); mp 146-147 °C. ¹H NMR (500 MHz, CDCl₃, TMS):
δ = 7.46 (s, 1 H), 7.36 (d, J = 7.8 Hz, 1 H), 7.24 (dd, J ₁ = J ₂ = 7.8 Hz, 1 H), 7.18 (s, 1 H), 7.17 (d, J = 7.8 Hz, 1 H), 6.68 (s, 1 H), 6.61 (s, 1 H), 4.59 (br, 1 H), 3.96 (s, 3 H), 3.89 (s, 3 H), 3.26 (br, 1 H), 3.12 (br, 1 H), 2.66 (br, 1 H), 1.07 (s, 9 H). ¹³C NMR (126 MHz, CDCl₃): d = 153.0, 149.5, 147.7, 139.1, 135.3, 134.2, 129.5, 128.3, 128.2, 126.7, 126.3, 125.0, 116.0, 111.7, 106.4, 80.6, 56.2, 55.9, 43.1, 28.3, 27.8.
IR (CHCl₃): 1685 cm^-1. MS (FAB): m/z = 415 [M⁺]. Anal. Calcd for C₂₃H₂₆ClNO₄: C, 66.42; H, 6.30; N, 3.37. Found: C, 66.38; H, 6.32; N, 3.35.