Synlett 2005(13): 2062-2066  
DOI: 10.1055/s-2005-871959
LETTER
© Georg Thieme Verlag Stuttgart · New York

Thermal and Au(I)-Catalyzed Intramolecular [4+2] Cycloaddition of Aryl-Substituted 1,6-Diynes for the Synthesis of Biaryl Compounds

Takanori Shibata*, Ryo Fujiwara, Daisuke Takano
Department of Chemistry, School of Science and Engineering, Waseda University, Shinjuku, Tokyo, 169-8555, Japan
e-Mail: tshibata@waseda.jp;
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Publikationsverlauf

Received 17 May 2005
Publikationsdatum:
13. Juli 2005 (online)

Abstract

1,6-Diynes, possessing aryl groups on their termini, undergo an intramolecular [4+2] cycloaddition via strained cyclic allene intermediates to give various biaryl compounds. Under thermal conditions, isomerization of the intermediates occurs, while, in the presence of a cationic gold catalyst, skeletal rearrangement is a ­major pathway.

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Typical experimental procedure for the Au(I)-catalyzed cycloaddition (Table [2] , entry 7): AuCl(PPh3) (1.0 mg, 0.0020 mmol) was placed in a flask, and a CH2Cl2 solution (8 mL) of diyne 1a (34.8 mg, 0.10 mmol) was added. To the resulting mixture was added AgSbF6 (0.8 mg, 0.0024 mmol), and the mixture was stirred at 0 °C for 5 h. The reaction was quenched by the addition of H2O (20 mL) and organic materials were extracted with CH2Cl2. The combined organic layer was dried over Na2SO4. The solvent was removed under reduced pressure, and the residue was purified by TLC to give products 2a (3.1 mg, 9%) and 3a (24.0 mg, 69%). 2a: Yellow oil; IR (neat): 825, 795, 775, 750, 739 cm-1; 1H NMR (400 MHz, CDCl3): δ = 2.01-2.15 (m, 2 H), 2.49-2.59 (m, 1 H), 2.67-2.77 (m, 1 H), 3.23-3.27 (m, 2 H), 7.19-7.30 (m, 3 H), 7.41-7.47 (m, 3 H), 7.50-7.54 (m, 1 H), 7.57-7.64 (m, 1 H), 7.77 (d, 1 H, J = 8.0 Hz), 7.93 (d, 2 H, J = 8.0 Hz), 8.68 (s, 1 H), 8.75 (d, 1 H, J = 8.4 Hz); 13C NMR (75 MHz, CDCl3): δ = 25.6, 32.3, 33.6, 100.5, 117.2, 122.6, 125.0, 125.5, 125.6, 125.8, 126.0, 126.1, 126.2, 127.4, 127.6, 128.2, 128.3, 129.5, 130.1, 130.4, 131.4, 132.3, 133.6, 133.7, 137.4, 143.2, 143.2; HRMS (FAB): m/z calcd for C27H20 (M+): 344.1565, found: 344.1562. 3a: Yellow oil; IR (neat) 823, 796, 779, 739
cm-1; 1H NMR (400 MHz, CDCl3): δ = 1.89-1.95 (m, 2 H), 2.50-2.63 (m, 2 H), 2.66-2.70 (m, 2 H), 7.04 (d, 1 H, J = 8.4 Hz), 7.31-7.40 (m, 2 H), 7.48-7.51 (m, 3 H), 7.56-7.60 (m, 2 H), 7.69 (dd, 1 H, J = 4.4 Hz, 4.4 Hz), 7.80 (d, 2 H, J = 8.4 Hz), 7.89-7.94 (m, 2 H), 8.42 (d, 1 H, J = 8.4 Hz); 13C NMR (75 MHz, CDCl3): δ = 24.2, 24.4, 27.5, 119.5, 123.0, 123.5, 125.5, 125.7, 125.8, 126.5, 126.7, 126.9, 127.0, 127.7, 128.0, 128.3, 129.4, 129.6, 131.9, 132.1, 132.9, 133.8, 134.3, 135.8, 136.5, 141.6, 143.7; HRMS (FAB): m/z calcd for C27H20 (M+): 344.1565, found: 344.1566.