Synthesis of Functionalized Diaryl Ethers by [3+3] Cyclization of 1,3-Bis(Silyl Enol Ethers) with 2-Aryloxy-3-(silyloxy)alk-2-en-1-ones

Abstract

Functionalized and sterically encumbered diaryl ethers were prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-aryloxy-3-(silyloxy)alk-2-en-1-ones.

arenes - cyclizations - diaryl ethers - silyl enol ethers

References and Notes

<A NAME="RD25406ST-1">1</A> Römpp Lexikon Naturstoffe   Steglich W. Fugmann B. Lang-Fugmann S. Thieme; Stuttgart: 1997. 

See, for example:

<A NAME="RD25406ST-2A">2a</A> Lee HJ. Lee JH. Hwang BY. Kim HS. Lee JJ. J. Antibiot.  2002,  55:  552 

<A NAME="RD25406ST-2B">2b</A> Hargreaves J. Park J.-O. Ghisalberti EL. Sivasithamparam K. Skelton BW. White AH. J. Nat. Prod.  2002,  65:  7 

<A NAME="RD25406ST-2C">2c</A> Hussein SAM. Ayoub NA. Nawwar MAM. Phytochemistry  2003,  63:  905 

<A NAME="RD25406ST-2D">2d</A> Nawwar MAM. Hussein SAM. Buddrus J. Linscheid M. Phytochemistry  1994,  35:  1349 

<A NAME="RD25406ST-2E">2e</A> Fiedler P. Gambaro V. Garbarino JA. Quilhot W. Phytochemistry  1986,  25:  461 

<A NAME="RD25406ST-2F">2f</A> Jolkianin: Lee S.-H. Tanaka T. Nonaka G.-i. Nishioka I. Chem. Pharm. Bull.  1991,  39:  630 

<A NAME="RD25406ST-2G">2g</A> Yoshida T. Ahmed AF. Okuda T. Chem. Pharm. Bull.  1993,  41:  672 

<A NAME="RD25406ST-2H">2h</A> Elix JA. Jones AJ. Lajide L. Coppins BJ. James PW. Aust. J. Chem.  1984,  37:  2349 

For a review, see:

<A NAME="RD25406ST-3A">3a</A> Moroz AA. Shvartsberg MS. Russ. Chem. Rev.  1974,  43:  679 

<A NAME="RD25406ST-3B">3b</A> For a recent example, see: Sinisi R. Sani M. Candiani G. Parente R. Pecker F. Bellosta S. Zanda M. Tetrahedron Lett.  2005,  46:  6515 ; and references cited therein

<A NAME="RD25406ST-4A">4a</A> Harkal S. Kumar K. Michalik D. Zapf A. Jackstell R. Rataboul F. Riermeier T. Monsees A. Beller M. Tetrahedron Lett.  2005,  46:  3237 ; and references cited therein

<A NAME="RD25406ST-4B">4b</A> Harkal S. Rataboul F. Zapf A. Fuhrmann C. Riermeier TH. Monsees A. Beller M. Adv. Synth. Catal.  2004,  346:  1742 

<A NAME="RD25406ST-4C">4c</A> Muci AR. Buchwald SR. Topics Curr. Chem.  2002,  219:  131 

<A NAME="RD25406ST-5A">5a</A> Chan T.-H. Brownbridge P. J. Am. Chem. Soc.  1980,  102:  3534 

<A NAME="RD25406ST-5B">5b</A> Brownbridge P. Chan T.-H. Brook MA. Kang GJ. Can. J. Chem.  1983,  61:  688 

<A NAME="RD25406ST-6">6</A> For a review of 1,3-bis(silyl enol ethers), see: Langer P. Synthesis  2002,  441 

<A NAME="RD25406ST-7A">7a</A> Dede R. Langer P. Tetrahedron Lett.  2004,  45:  9177 

<A NAME="RD25406ST-7B">7b</A> Nguyen V. Langer P. Tetrahedron Lett.  2005,  46:  1013 

<A NAME="RD25406ST-7C">7c</A> Ahmed Z. Fischer C. Spannenberg A. Langer P. Tetrahedron  2006,  62:  4800 

<A NAME="RD25406ST-7D">7d</A> Nguyen VTH. Bellur E. Appel B. Langer P. Synthesis  2006,  1103 

<A NAME="RD25406ST-7E">7e</A> Nguyen VTH. Bellur E. Langer P. Tetrahedron Lett.  2006,  47:  113 

<A NAME="RD25406ST-7F">7f</A> Mamat C. Pundt T. Schmidt A. Langer P. Tetrahedron Lett.  2006,  47:  2183 

<A NAME="RD25406ST-7G">7g</A> Ahmed Z. Langer P. Tetrahedron Lett.  2006,  47:  417 

<A NAME="RD25406ST-8">8</A> Beer RJS. Davenport HF. Robertson A. J. Chem. Soc.  1953,  1262 

<A NAME="RD25406ST-9">9</A>

General Procedure for the Synthesis of Diaryl Ethers 6a-n.
To a CH₂Cl₂ solution (2 mL/mmol) of 4 (1.0 mmol) and 5 (1.0 mmol) was added TiCl₄ (1.0 mmol) at -78 °C. The solution was allowed to warm to ambient temperature within 20 h. To the solution was added a sat. solution of NaHCO₃ (10 mL). The organic and the aqueous layer were separated and the latter was extracted with Et₂O (3 × 30 mL). The filtrate was concentrated in vacuo and the residue was puri-fied by chromatography (silica gel, EtOAc-n-heptane, 1:4).
Synthesis of Methyl 4,6-Dimethyl-5-(4-chloro-phenoxy)salicylate ( 6h).
Starting with 1,3-bis(silyl enol ether) 5d (500 mg, 1.9 mmol), 3-(siloxy)alk-2-en-1-one 4d (574 mg, 1.9 mmol) and TiCl₄ (0.21 mL, 1.9 mmol), 6h was isolated as a colorless solid (315 mg, 54%); mp 83 °C. ¹H NMR (300 MHz, CDCl₃): δ = 2.09 (s, 3 H, CH₃), 2.30 (s, 3 H, CH₃), 3.95 (s, 3 H, OCH₃), 6.67 (d, 2 H, J = 9.0 Hz, ArH), 6.76 (s, 1 H, ArH), 7.20 (d, 2 H, J = 9.0 Hz, ArH), 11.10 (s, 1 H, OH). ¹³C NMR (75 MHz, CDCl₃): δ = 15.2, 17.1, 52.2 (CH₃), 111.1 (C), 115.7 (2 C), 117.6 (CH), 126.3 (C), 129.6 (2 C, CH), 133.5, 139.7, 143.6, 156.5, 159.7, 171.7 (C). IR (KBr): 3431 (m), 2959 (w), 1661 (s), 1486 (s), 1442 (m), 1361 (m), 1326 (s), 1318 (s), 1074 (m), 825 (m), 803 (m) cm^-1. GC-MS (EI, 70 eV): m/z (%) = 306 (33) [M⁺], 274 (100), 246 (10), 163.1 (8). Anal. Calcd (%) for C₁₆H₁₅ClO₄ (306.74): C, 62.65; H, 4.93. Found: C, 62.42; H, 4.68.