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Synlett 2004(10): 1691-1694  
DOI: 10.1055/s-2004-829551
LETTER
© Georg Thieme Verlag Stuttgart · New York

An Efficient Ring-Opening Reaction of Aziridines with Alkynes Catalyzed by CuOTf

Chang-Hua Dingb, Li-Xin Daia, Xue-Long Hou*a,b
a State Key Laboratory of Organometallic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China
b Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China
e-Mail: xlhou@mail.sioc.ac.cn;
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Publication History

Received 9 April 2004
Publication Date:
15 July 2004 (online)

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Abstract

The alkynylation of activated aziridines in the presence of a catalytic amount of CuOTf provided the corresponding ring-opened products in high yields.

Key words

aziridines - alkynylation - Lewis acids - copper(I) triflate - ring-opening reaction

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General Experimental Procedure: Alkyne (0.5 mmol) was added to a mixture of n-BuLi in n-hexane (0.5 mmol) and Et2O (4.0 mL), which was precooled to -78 °C and the mixture was stirred for 30 min at the same temperature. Then CuOTf (10 mol%) and aziridine (0.25 mmol) were added. The resulting mixture was stirred at r.t. until complete consumption of substrate (monitored by TLC). The reaction mixture was quenched with 5 mL of sat. NH4Cl aq solution. The aqueous layer was separated and extracted with CH2Cl2 (3 ¥ 10 mL). The combined organic layer was dried over anhyd Na2SO4. The solvent was removed in vacuum and the crude product was purified by flash column chromatography on silica gel to provide corresponding homopropargyl amine. All products were fully characterized by 1H NMR, mass spectrometry, infrared spectrometry and elemental analysis. The 1H NMR spectra of the products are as follows (300 MHz, CDCl3, 25 °C, TMS):
N -(2-Phenyl-1-ynyl-cyclohexyl)-4-methyl-benzene-sulfonamide (2a): 1H NMR: δ = 1.24-1.27 (m, 4 H), 1.46-1.69 (m, 2 H), 1.99-2.05 (m, 1 H), 2.24-2.28 (m, 1 H), 2.31 (s, 3 H), 2.41-2.49 (m, 1 H), 3.02-3.12 (m, 1 H), 4.81 (d, J = 5.4 Hz, 1 H), 7.11 (d, J = 8.1 Hz, 2 H), 7.12-7.29 (m, 5 H), 7.75 (d, J = 8.4 Hz, 2 H).
N -(2-phenyl-1-ynyl-cyclopentyl)-4-methyl-benzene-sulfonamide (2b): 1H NMR: δ = 1.45-1.53 (m, 1 H), 1.68-1.75 (m, 3 H), 2.04-2.15 (m, 2 H), 2.32 (s, 3 H), 2.69-2.74 (m, 1 H), 3.52-3.56 (m, 1 H), 4.80 (d, J = 6.0 Hz, 1 H), 7.20 (d, J = 8.1 Hz, 2 H), 7.23-7.29 (m, 5 H), 7.78-7.82 (m, 2 H).
N -(2-phenyl-1-ynyl-cyclohexyl)-benzenesulfonamide (2c): 1H NMR: δ = 1.21-1.69 (m, 6 H), 1.99-2.05 (m, 1 H), 2.23-2.27 (m, 1 H), 2.42-2.50 (m, 1 H), 3.07-3.13 (m, 1 H), 4.88 (d, J = 5.4 Hz, 1 H), 7.24-7.47 (m, 8 H), 7.87-7.89 (m, 2 H).
N -(2-trimethylsilanyl-1-ynyl-cyclohexyl)-4-methyl-benzenesulfonamide (2aa): 1H NMR: δ = 0.13 (s, 9 H), 1.48-1.64 (m, 6 H), 1.89-1.94 (m, 1 H), 2.21-2.33 (m, 2 H), 2.43 (s, 3 H), 2.89-2.94 (m, 1 H), 4.80 (d, J = 3.6 Hz, 1 H), 7.31 (d, J = 8.4 Hz, 2 H), 7.78 (d, J = 8.4 Hz, 2 H).
1-Phenyl-4- N -( p -toluenesulfonyl)aminooctyne-1 (2d): 1H NMR: δ = 0.82 (t, J = 6.6 Hz, 3 H), 1.19-1.25 (m, 4 H), 1.56-1.62 (m, 2 H), 2.41 (s, 3 H), 2.48 (d, J = 5.1 Hz, 2 H), 3.36-3.46 (m, 1 H), 4.71 (d, J = 9.3 Hz, 1 H), 7.26-7.37 (m, 7 H), 7.78 (d, J = 8.1 Hz, 2 H).
1-Phenyl-5,5-dimethyl-4- N -( p -toluenesulfonyl)amino-hexyne-1 (2e): 1H NMR: d = 0.98 (s, 9H), 2.28-2.36 (m, 1H), 2.39 (s, 3H), 2.49-2.56 (m, 1H), 3.16-3.23 (m, 1H), 4.89 (d, J = 10.5 Hz, 1H), 7.24-7.35 (m, 7H), 7.79 (d, J = 8.1 Hz, 2H).
1-Phenyl-4- N -( p -toluenesulfonyl)aminodecyne-1 (2f):
1H NMR: δ = 0.85 (t, J = 6.9 Hz, 3 H), 1.17-1.29 (m, 8 H), 1.52-1.62 (m, 2 H), 2.41 (s, 3 H), 2.50 (d, J = 4.8 Hz, 2 H), 3.37-3.45 (m, 1 H), 4.67 (d, J = 9.0 Hz, 1 H), 7.26-7.38 (m, 7 H), 7.78 (d, J = 8.1 Hz, 2 H).
1-Phenyl-4- N -( p -toluenesulfonyl)aminoicosyne-1 (2g): 1H NMR: δ = 0.88 (t, J = 6.6 Hz, 3 H), 1.17-1.30 (m, 28 H), 1.57-1.64 (m, 2 H), 2.41 (s, 3 H), 2.49 (d, J = 4.8 Hz, 2 H), 3.36-3.44 (m, 1 H), 4.65 (d, J = 9.3 Hz, 1 H), 7.26-7.38 (m, 7 H), 7.77-7.79 (m, 2 H).
1-Trimethylsilanyl-4- N -( p -toluenesulfonyl)amino-decyne-1 (2fa): 1H NMR: δ = 0.15 (s, 9 H), 0.85 (t, J = 6.9 Hz, 3 H), 1.15-1.26 (m, 8 H), 1.88-2.04 (m, 2 H), 2.27-2.31 (m, 2 H), 2.43 (s, 3 H), 3.28-3.33 (m, 1 H), 4.61 (d, J = 9.0 Hz, 1 H), 7.30 (d, J = 7.5 Hz, 2 H), 7.76 (d, J = 8.4 Hz, 2 H).
8- N -( p -toluenesulfonyl)aminotetradecyne-5 (2fb): 1H NMR: δ = 0.85 (t, J = 6.6 Hz, 3 H), 0.91 (t, J = 7.2 Hz, 3 H), 1.16-1.25 (m, 8 H), 1.38-1.47 (m, 6 H), 2.12-2.16 (m, 2 H), 2.17-2.21 (m, 2 H), 2.43 (s, 3 H), 3.24-3.31 (m, 1 H), 4.63 (d, J = 9.6 Hz, 1 H), 7.29 (d, J = 7.5 Hz, 2 H), 7.75-7.78 (m, 2 H).
1,4-Diphenyl-4- N -( p -toluenesulfonyl)aminobutyne-1 (2h) and 1,3-Diphenyl-4- N -( p -toluenesulfonyl)amino-butyne-1 (3h): (2h/3h = 3:1) 1H NMR: 2h: δ = 2.35 (s, 3 H), 2.85 (m, 2 H), 4.56 (dd, J = 6.3, 12.8 Hz, 1 H), 5.20 (d, J = 6.6 Hz, 1 H), 7.12-7.41 (m, 12 H), 7.63 (d, J = 8.4 Hz, 2 H); 3h: δ = 2.41 (s, 3 H), 3.21-3.41 (m, 2 H), 3.99 (dd, J = 6.3, 8.1 Hz, 1 H), 4.72-4.76 (m, 1 H), 7.12-7.41 (m, 12 H), 7.73 (d, J = 8.4 Hz, 2 H).