m-Terphenyl Ethers, a New Hydroxy Protecting Group Cleavable under Reductive Single Electron Transfer Reaction Conditions

Abstract

m-Terphenyl ethers and, to a lesser extent, 2,6-dimeth­oxyphenyl ethers, were tested as protected hydroxy derivatives under a variety of reaction conditions. These ethers underwent regioselective cleavage of the aromatic C(1)-O bond under reductive SET reaction conditions using alkali metals in tetrahydrofuran at room temperature. This deprotective procedure was efficiently realized in the presence of several other functional groups, including an acetal, a phenyl alkyl ether, an unprotected alcohol, and carbon-carbon double and triple bonds. Furthermore, m-terphenyl ethers proved stable under different reaction conditions, including acidic hydrolysis and formation and/or employment of different organometallic reagents.

Key words

alcohols - electron transfer - protecting groups - reduction - sodium

References

• 1 Greene TW. Wuts PGM. Protective Groups in Organic Synthesis   John Wiley & Sons; New York: 2007. 
• 2 Kocienski P. Protecting Groups   Georg Thieme Verlag; Stuttgart: 2003. 
• 3 Alonso E. Ramón DJ. Yus M. Tetrahedron  1997,  53:  14355 
• 4 Liu H.-J. Yip J. Shia K.-S. Tetrahedron Lett.  1997,  38:  2253 
• 5 Yus M. Behloul C. Guijarro D. Synthesis  2003,  2179 
• 6 Azzena U. Trends Org. Chem.  1997,  6:  55 ; and references therein
• See, for example:
• 7a Pisano L. Farriol M. Asensio X. Gallardo I. Gonzàlez-Lafont A. Lluch J.-M. Marquet J. J. Am. Chem. Soc.  2002,  124:  4708 
• 7b Azzena U. Casado F. Fois P. Gallardo I. Pisano L. Marquet J. Melloni G. J. Chem. Soc., Perkin Trans. 2  1996,  2563 
• 7c Azzena U. Denurra T. Melloni G. Fenude E. Rassu G. J. Org. Chem.  1992,  57:  1444 
• See, for example:
• 8a Azzena U. Dettori G. Mascia I. Pisano L. Pittalis M. Tetrahedron  2007,  63:  11998 
• 8b Azzena U. Dettori G. Idini MV. Pisano L. Sechi G. Tetrahedron  2003,  59:  7961 
• 8c Azzena U. Melloni G. Pisano L. J. Chem. Soc., Perkin Trans. 1  1995,  261 
• 8d Azzena U. Melloni G. Piroddi AM. Azara E. Contini S. Fenude E. J. Org. Chem.  1992,  57:  3101 ; and references therein
• 9 Azzena U. Denurra T. Melloni G. Piroddi AM. J. Org. Chem.  1990,  55:  5386 
• 10 Casado F. Pisano L. Farriol M. Gallardo I. Marquet J. Melloni G. J. Org. Chem.  2000,  65:  322 
• 11 Lepore SD. He Y. J. Org. Chem.  2003,  68:  8261 
• 12 For a comparison of the electrode potentials of the alkali metals, see: Hwu JR. Wein YS. Leu Y.-J. J. Org. Chem.  1996,  61:  1493 
• 13 Stoochnoff BA. Benoiton NL. Tetrahedron Lett.  1973,  14:  21 
• 14 Hanada S. Yuasa A. Kuroiwa H. Motoyama Y. Nagashima H. Eur. J. Org. Chem.  2010,  1021 
• 15 Fuller JC. Stangeland EL. Jackson TC. Singaram B. Tetrahedron Lett.  1994,  35:  1515 
• 16 Bothwell JM. Angeles VV. Carolan JP. Olson ME. Mohan RS. Tetrahedron Lett.  2010,  51:  1056 
• 17 Murphy JA. Schoenebeck F. Findlay NJ. Thomson DW. Zhou SZ. Garnier J. J. Am. Chem. Soc.  2009,  131:  6475