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

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.

cycloaddition - diynes - arylalkynes - gold - biaryl compounds

References

<A NAME="RU15705ST-1A">1a</A> Dykstra HB. J. Am. Chem. Soc.  1934,  56:  1625 

<A NAME="RU15705ST-1B">1b</A> Butz LW. Joshel LM. J. Org. Chem.  1941,  6:  3344 

<A NAME="RU15705ST-1C">1c</A> Butz LW. Joshel LM. J. Org. Chem.  1942,  7:  1311 

<A NAME="RU15705ST-2">2</A> Danheiser RL. Gould AE. Pradilla GRF. Helgason AL. J. Org. Chem.  1994,  59:  5514 

<A NAME="RU15705ST-3">3</A> Burrell RC. Daoust KJ. Bradley AZ. DiRico KJ. Johnson RP. J. Am. Chem. Soc.  1996,  118:  4218 

<A NAME="RU15705ST-4A">4a</A> Rodríguez D. Navarro A. Castedo L. Domínguez D. Saá C. Org. Lett.  2000,  2:  1497 

<A NAME="RU15705ST-4B">4b</A> Rodríguez D. Navarro-Vázquez A. Castedo L. Domínguez D. Saá C. J. Am. Chem. Soc.  2001,  123:  9178 

<A NAME="RU15705ST-4C">4c</A> Rodríguez D. Navarro-Vázquez A. Castedo L. Domínguez D. Saá C. J. Org. Chem.  2003,  68:  1938 

<A NAME="RU15705ST-4D">4d</A> Rodríguez D. Martínez-Esperón MF. Castedo L. Domínguez D. Saá C. Synlett  2003,  1524 

<A NAME="RU15705ST-4E">4e</A> Rodríguez D. Castedo L. Domínguez D. Sáa C. Synlett  2004,  761 

<A NAME="RU15705ST-4F">4f</A> Rodríguez D. Martínez-Esperón MF. Navarro-Vázquez A. Castedo L. Domínguez D. Saá C. J. Org. Chem.  2004,  69:  3842 

<A NAME="RU15705ST-5">5</A> Atienza C. Mateo C. de Frutos Ó. Echavarren AE. Org. Lett.  2001,  3:  153 

Pt:

<A NAME="RU15705ST-6A">6a</A> Fürstner A. Szillat H. Stelzer F. J. Am. Chem. Soc.  2001,  122:  6785 

<A NAME="RU15705ST-6B">6b</A> Méndez M. Muñoz MP. Nevado C. Cárdenas DJ. Echavarren AM. J. Am. Chem. Soc.  2001,  122:  10511 

<A NAME="RU15705ST-6C">6c</A> Oi S. Tsukamoto I. Miyano S. Inoue Y. Organometallics  2001,  20:  3704 

Au(III):

<A NAME="RU15705ST-6D">6d</A> Asao N. Takahashi K. Lee S. Kasahara T. Yamamoto Y. J. Am. Chem. Soc.  2002,  124:  12650 

<A NAME="RU15705ST-6E">6e</A> Asao N. Aikawa H. Yamamoto Y. J. Am. Chem. Soc.  2004,  7458 

<A NAME="RU15705ST-6F">6f</A> Zhang L. Kozmin SA. J. Am. Chem. Soc.  2005,  127:  6962 

<A NAME="RU15705ST-6G">6g</A> Cu(II): Asao N. Nogami T. Lee S. Yamamoto Y. J. Am. Chem. Soc.  2003,  125:  10921 

<A NAME="RU15705ST-7">7</A> Shibata T. Fujiwara R. Ueno Y. Synlett  2005,  152 

Recent examples where Au(I) salts were used as Lewis acid catalysts:

<A NAME="RU15705ST-8A">8a</A> Nieto-Oberhuber C. Muñoz MP. Buñuel E. Nevado C. Cárdenas DJ. Echavarren AM. Angew. Chem. Int. Ed.  2004,  43:  2402 

<A NAME="RU15705ST-8B">8b</A> Kennedy-Smith JJ. Staben ST. Toste FD. J. Am. Chem. Soc.  2004,  126:  4526 

<A NAME="RU15705ST-8C">8c</A> Luzung MR. Markham JP. Toste FD. J. Am. Chem. Soc.  2004,  126:  10858 

<A NAME="RU15705ST-8D">8d</A> Zhang L. Kozmin SA. J. Am. Chem. Soc.  2004,  126:  11806 

<A NAME="RU15705ST-8E">8e</A> Sherry BD. Toste FD. J. Am. Chem. Soc.  2004,  126:  15978 

<A NAME="RU15705ST-8F">8f</A> Shi X. Gorin DJ. Toste FD. J. Am. Chem. Soc.  2005,  127:  5802 

<A NAME="RU15705ST-9">9</A> Under the reaction conditions, AgSbF₆ did not operate as a catalyst by itself: Yamaguchi Y. Kobayashi S. Wakamiya T. Matsubara Y. Yoshida Z. J. Am. Chem. Soc.  2000,  122:  7404 

<A NAME="RU15705ST-10">10</A>

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.

<A NAME="RU15705ST-11">11</A> During our preparation of this manuscript, Au(I)-catalyzed intramolecular [4+2] cycloaddition of arylalkynes and alkenes was reported, and a mechanism via 3-membered ring intermediate was proposed. In the present cycloaddition of arylalkynes and alkynes, the formation of cyclopropene by the same reaction mechanism could hardly be possible: Nieto-Oberhuber C. Lopez S. Echavarren AM. J. Am. Chem. Soc.  2005,  127:  6178