Synlett 2012(1): 74-79  
DOI: 10.1055/s-0031-1289867
CLUSTER
© Georg Thieme Verlag Stuttgart ˙ New York

Gold-Catalyzed Cycloisomerization of Functionalized 1,5-Enynes - An Entry to Polycyclic Framework

Alexandre Pradala,b,¹, Qian Chena,b,¹, Pierre Faudot dit Bela,b, Patrick Yves Toullec*a,b, Véronique Michelet*a,b
a Chimie ParisTech, Laboratoire Charles Friedel (LCF), 11, rue P. et M. Curie, 75231 Paris Cedex 05, France
Fax: +33(1)44071062; e-Mail: patrick-toullec@chimie-paristech.fr; e-Mail: veronique-michelet@chimie-paristech.fr;
b CNRS, UMR 7223, 75231 Paris Cedex 05, France
Further Information

Publication History

Received 12 September 2011
Publication Date:
11 November 2011 (online)

Abstract

The gold-catalyzed cycloisomerization reactions of variously functionalized 1,5-enynes are presented. The cyclization processes implying aryl- and 1,3-dicarbonyl-substituted skeletons are conducted under mild conditions and lead to cyclic structures obtained according to 6-endo-dig or 5-endo-dig mode depending on the involved nucleophilic partner. Some competitive pathways and trapping of carbocationic intermediates are highlighted.

1

These two authors contributed equally to this work.

11

Typical Procedure for the Gold-Catalyzed Reactions of 1,5-Enynes
PPh3AuCl (3.3 mg, 0.0066 mmol) and AgSbF6 (2.3 mg, 0.0066 mmol) were added to a flask under argon atmos-phere. Then, anhyd Et2O (0.44 mL) and 10 (60 mg, 0.22 mmol) were introduced, and the mixture was stirred for 1 h at r.t. After filtration of the reactant, the solvent was evaporated under reduced pressure. The residue was purified by flash chromatography (cyclohexane-EtOAc, 100:1) on silica gel to give 21 (55 mg, 92% yield) as a colorless oil.

13

2-[(4-Methoxyphenoxy)methyl]-1,3-dimethylcyclohex-3-enol (23)
¹H NMR (400 MHz, CDCl3): δ = 1.27 (6 H, m), 1.76-1.75 (4 H, m), 2.50 (1 H, m), 3.77 (3 H, s), 3.94-3.92 (1 H, dd, J = 5.8, 7.3 Hz), 4.12-4.08 (1 H, dd, J = 3.0, 7.3 Hz), 5.50 (1 H, t, J = 1.2 Hz), 6.87-6.77 (4 H, m). ¹³C NMR (100 MHz, CDCl3): δ = 22.3, 23.0, 24.8, 33.7, 50.5, 55.8, 68.9, 71.6, 76.8, 77.1, 77.4, 114.7, 115.7, 123.7, 131.6, 152.7, 154.2. MS (CI): m/z = 245 [M - H2O + H]+, 262 [M - H2O + NH4]+, 263 [M + H]+, 280 [M + NH4]+.

16

3-(3,5-Dimethoxybenzyl)-5-methylbicyclo[3.1.0]hex-2-ene (25) and 1,2-Dihydro-5,7-dimethoxy-2-(2-methylallyl)naphthalene (24)
Compound 25: ¹H NMR (300 MHz, CDCl3): δ = 0.09 (1 H, dd, J = 3.4, 2.4 Hz), 0.67 (1 H, dd, J = 7.2, 3.5 Hz), 1.24 (3 H, s), 1.41-1.44 (1 H, m), 2.25 (2 H, s), 3.22 (2 H, s), 3.78 (6 H, s), 5.60 (1 H, d, J = 1.7 Hz), 6.30 (3 H, s). ¹³C NMR (75 MHz, CDCl3): δ = 21.8, 22.6, 24.1, 29.9, 37.9, 43.8, 55.2, 97.9, 106.8, 130.3, 141.4, 142.6, 160.7.
Compound 24: ¹H NMR (300 MHz, CDCl3): δ = 1.73 (3 H, s), 1.70-1.84 (1 H, m), 2.10-2.15 (1 H, m), 2.50-2.70 (2 H, m), 2.75-2.80 (1 H, m), 3.80 (6 H, s), 4.72 (1 H, br s), 4.82 (1 H, br s), 5.75-5.85 (1 H, m), 6.30-6.36 (2 H, m), 6.70-6.77 (1 H, m). ¹³C NMR (75 MHz, CDCl3): δ = 22.2, 31.3, 34.4, 42.5, 55.0, 55.5, 96.3, 105.1, 112.1, 115.6, 120.6, 129.4, 137.5, 143.5, 156.0, 159.0. MS (CI): m/z = 245 [M + H]+.
3-(3,5-Dimethoxybenzyl)-5-methyl-1-phenylbicyclo-[3.1.0]hex-2-ene(27) and 1,2-Dihydro-5,7-dimethoxy-2-(2-methylallyl)-4-phenylnaphthalene (26)
Compound 27: ¹H NMR (300 MHz, CDCl3): δ = 0.64 (1 H, d, J = 4.1 Hz), 0.96 (3 H, s), 1.35 (1 H, d, J = 4.1 Hz), 2.40 (2 H, s), 3.33 (2 H, s), 3.79 (6 H, s), 5.72 (1 H, s), 6.26-6.37 (3 H, m), 7.15-7.31 (5 H, m). ¹³C NMR (75 MHz, CDCl3):
δ = 18.6, 27.1, 30.4, 37.8, 43.0, 45.0, 55.2, 97.9, 106.8, 125.7, 128.0, 128.3, 133.4, 140.3, 141.3, 142.5, 160.8.
Compound 26: ¹H NMR (300 MHz, CDCl3): δ = 1.75 (3 H, s), 1.70-1.84 (1 H, m), 2.20-2.28 (1 H, m), 2.50-2.70 (2 H, m), 2.75-2.80 (1 H, m), 3.74 (3 H, s), 3.79 (3 H, s), 4.72 (1 H, br s), 4.82 (1 H, br s), 5.83-5.85 (1 H, m), 6.25-6.37 (2 H, m), 7.15-7.31 (5 H, m). ¹³C NMR (75 MHz, CDCl3): δ = 22.3, 32.1, 36.6, 42.2, 55.1, 55.2, 97.3, 101.0, 104.8, 112.1, 125.2, 125.8, 126.8, 132.4, 137.6, 141.0, 143.5, 157.5, 158.1, 159.6. MS (CI): m/z = 321 [M + H]+.
3-Benzyl-5-methylbicyclo[3.1.0]hex-2-ene (29)
Colorless oil. ¹H NMR (300 MHz, CDCl3): δ = 0.09 (1 H, dd, J = 3.4, 3.3 Hz), 0.67 (1 H, dd, J = 7.3, 3.5 Hz), 1.24 (3 H, s), 1.41-1.43 (1 H, m), 2.25 (2 H, s), 3.28 (2 H, s), 5.56 (1 H, br s), 7.12-7.30 (5 H, m). ¹³C NMR (75 MHz, CDCl3): δ = 21.8, 22.6, 24.2, 29.9, 37.6, 43.9, 125.8, 128.2, 128.7, 130.0, 139.0, 142.0. MS (CI): m/z = 184 [M]+.
3-Benzyl-5-methyl-1-phenylbicyclo[3.1.0]hex-2-ene (31)
Colorless oil. ¹H NMR (300 MHz, CDCl3): δ = 0.63 (1 H, d, J = 4.1 Hz), 0.95 (3 H, s), 1.34 (1 H, d, J = 4.1 Hz), 2.40 (2 H, s), 3.39 (2 H, s), 5.67 (1 H, s), 7.18-7.22 (6 H, m), 7.26-7.31 (4 H, m). ¹³C NMR (75 MHz, CDCl3): δ = 18.6, 27.2, 30.4, 37.4, 43.0, 45.1, 125.7, 125.9, 127.9, 128.3, 128.8, 133.2, 140.0, 140.4, 141.8. MS (CI): m/z = 260 [M]+.

21

Methyl 5-(1,2-dimethylcyclopent-2-en-1-yl)-2-methyl-4,5-dihydrofuran-3-carboxylate (37)
¹H NMR (300 MHz, CDCl3): δ = 1.07 (3 H, s), 1.60-1.67 (4 H, m), 1.87 (1 H, m), 2.16 (3 H, s), 2.16-2.25 (2 H, m), 2.65-2.81 (2 H, m), 3.71 (3 H, s), 4.59 (1 H, t, J = 10.2 Hz), 5.40 (1 H, br s). ¹³C NMR (75 MHz, CDCl3): δ = 12.9, 14.1, 21.5, 29.0, 31.7, 32.3, 50.6, 53.1, 86.6, 101.9, 126.1, 143.2, 166.7, 168.7. MS (CI): m/z = 237 [M + H]+.
1,2-(Dimethylcyclopent-2-en-1-yl)-2-phenyl-4,5-dihydrofuran-3-yl)(phenyl)methanone (38)
¹H NMR (300 MHz, CDCl3): δ = 1.17 (3 H, s), 1.67 (1 H, m), 1.74 (3 H, s), 2.04 (1 H, m), 2.23-2.27 (2 H, m), 3.19, 3.14 (2 H, 2 dd, J = 15.0, 10.3 Hz), 4.83 (1 H, t, J = 10.3 Hz), 5.43 (1 H, br s), 6.99-7.20 (8 H, m), 7.39 (2 H, dd, J = 1.4, 8.4 Hz). ¹³C NMR (75MHz, CDCl3): δ = 13.3, 21.6, 29.1, 33.0, 34.8, 53.2, 86.8, 112.7, 126.3, 127.5, 127.6, 128.8, 129.3, 129.8, 130.3, 130.9, 139.3, 143.2, 166.7, 193.7. MS (CI):
m/z = 345 [M + H]+.