Dearomatizing Anionic Cyclization of 1-Lithio-4-naphthyl-1,3-butadienes Leading to the Formation of Spiro Cyclopentadiene Derivatives

Abstract

On treatment with t-BuLi, 1-iodo-4-naphthyl-1,3-buta­diene derivatives cyclize with dearomatization to give spiro compounds bearing a moiety of allyllithium, which reacts further with electrophiles to yield spiro tricyclic systems.

anionic cyclization - cyclopentadiene derivative - de­aromatization - 1-lithio-4-naphthyl-1,3-butadiene - organolithium

References and Notes

<A NAME="RW33205ST-1A">1a</A> Clayden J. Organolithiums: Selectivity for Synthesis   Tetrahedron Organic Chemistry Series, Pergamon; Oxford: 2002.  Vol. 23:  p.282-335  ; and references cited therein

<A NAME="RW33205ST-1B">1b</A> Varela JA. Saa C. Chem. Rev.  2003,  103:  3787 

<A NAME="RW33205ST-1C">1c</A> Xi Z. Eur. J. Org. Chem.  2004,  2773 

<A NAME="RW33205ST-1D">1d</A> Foubelo F. Yus M. Curr. Org. Chem.  2005,  9:  459 

<A NAME="RW33205ST-2A">2a</A> Clayden J. Turnbull R. Pinto I. Tetrahedron: Asymmetry  2005,  16:  2235 

<A NAME="RW33205ST-2B">2b</A> Clayden J. Turnbull R. Pinto I. Org. Lett.  2004,  6:  609 

<A NAME="RW33205ST-2C">2c</A> Clayden J. Turnbull R. Helliwell M. Pinto I. Chem. Commun.  2004,  2430 

<A NAME="RW33205ST-2D">2d</A> Clayden J. Kenworthy MN. Synthesis  2004,  1721 

<A NAME="RW33205ST-2E">2e</A> Clayden J. Organolithiums: Selectivity for Synthesis   Tetrahedron Organic Chemistry Series, Pergamon; Oxford: 2002.  Vol. 23:  p.327-329  

<A NAME="RW33205ST-2F">2f</A> For a recent application of dearomatizing cyclization in synthesis, see: Clayden J. Knowles FE. Baldwin IR. J. Am. Chem. Soc.  2005,  127:  2412 

<A NAME="RW33205ST-3A">3a</A> Clayden J. Hamilton SD. Mohammed RT. Org. Lett.  2005,  7:  3673 

See also:

<A NAME="RW33205ST-3B">3b</A> Fraenkel G. Ho CC. Liang Y. Yu S. J. Am. Chem. Soc.  1972,  94:  4732 

<A NAME="RW33205ST-3C">3c</A> Foos J. Steel F. Rizvi SQA. Fraenkel G. J. Org. Chem.  1979,  44:  2522 

<A NAME="RW33205ST-4">4</A> Chen J. Song Q. Wang C. Xi Z. J. Am. Chem. Soc.  2002,  124:  6238 

<A NAME="RW33205ST-5">5</A> Song Q. Li Z. Chen J. Wang C. Xi Z. Org. Lett.  2002,  4:  4627 

<A NAME="RW33205ST-6">6</A> Fang H. Song Q. Wang Z. Xi Z. Tetrahedron Lett.  2004,  45:  5159 

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<A NAME="RW33205ST-8">8</A> Xi Z. Zhang W. Song Z. Zheng W. Kong F. Takahashi T. J. Org. Chem.  2005,  70:  8785 

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<A NAME="RW33205ST-10">10</A>

Typical Procedure for the Formation of 7a.
A solution of t-BuLi (2.0 equiv of a 1.5 M solution in pentane) was added dropwise to a stirred solution of compound 1a (209 mg, 0.5 mmol) in Et₂O (5 mL) at -78 °C under N₂. The reaction was stirred at the same temperature for 1 h, then TMSCl (108 mg, 1.0 mmol) was added. After the reaction was stirred for another 1 h at -78 °C, aq NaHCO₃ was added. The layers were separated, and the aqueous phase was extracted with Et₂O (3 ×). The combined extracts were washed with brine and dried over MgSO₄. Evaporation under reduced pressure gave a crude product which was purified by flash chromatography to yield product 7a. Colorless liquid, isolated yield 73% (133 mg). ¹H NMR (CDCl₃): δ = 0.10 (s, 9 H), 0.64 (t, J = 7.5 Hz, 3 H), 0.85 (t, J = 7.8 Hz, 3 H), 1.06-1.15 (m, 6 H), 1.86-2.34 (m, 8 H), 3.18 (t, J = 3.3 Hz, 1 H), 4.85 (dd, J = 10.2, 2.4 Hz, 1 H), 5.96 (dd, J = 10.2, 3.6 Hz, 1 H), 6.55 (dd, J = 7.5, 1.2 Hz, 1 H), 6.82-6.87 (m, 1 H), 6.97-7.06 (m, 2 H). ¹³C NMR (CDCl₃): δ = -1.52, 14.78, 15.00, 15.18, 15.68, 18.84, 18.87, 19.26, 19.37, 33.00, 62.90, 124.56, 125.35, 125.54, 125.85, 127.61, 127.77, 133.38, 136.50, 139.97, 142.04, 151.73, 152.44. HRMS: m/z calcd for C₂₅H₃₆Si: 364.2586; found: 364.2589.

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The deposition number at the Cambridge Crystallographic Data Centre: CCDC 295391.