References
- Saito , N. , Tashiro , K. , Maru , Y. , Yamaguchi , K. and Kubo , A. 1997 . J. Chem. Soc., Perkin Trans. 1 , : 53
- Saito , N. , Kamayachi , H. , Tachi , M. and Kubo , A. 1999 . Heterocycles , 51 : 9
- Shinhababu , A. K. and Borchardt , R. T. 1983 . Synth. Commun. , 13 : 677
- Nguyan , L. M. , Pan , H. T. , Van Diep , V. , Floret , S. , Azoulay , R. , Niesor , E. , Bentzen , C. L. and Ife , R. J. 1998 . Chem. Abstr. , 129 : 95613 PCT Int. Appl. WO 98 28, 310;
- Borchardt , R. T. and Bhatia , P. 1982 . J. Med. Chem. , 25 : 26
- Isopropyl ether as useful phenolic protective group was introduced by Simpson6 and popularized by Sargent7 and Stermitz.8
- Simpson , T. H. 1963 . J. Org. Chem. , 28 : 2107
- Sala , T. and Sargent , M. V. 1979 . J. Chem. Soc., Perkin Trans. 1 , : 2593
- Gillespie , J. P. , Amorous , L. G. and Stermitz , F. R. 1974 . J. Org. Chem. , 39 : 3239
- Vickery , E. H. , Pahler , L. F. and Eisenbraun , E. J. 1979 . J. Org. Chem. , 44 : 4444 also see:
- Jardon , P. W. , Vickery , E. H. , Pahler , L. F. , Pourahmady , N. , Mains , G. J. and Eisenbraun , E. J. 1984 . J. Org. Chem. , 49 : 2130
- The structures of 5a and 5b were supported by 1H-NMR spectra of 3-isopropioxy-2-methoxytoluene 7 and 13 2-isopropioxy-3-methyltoluene, which was obtained by methylation of 5b (88%). (13b δ 1.28 (6H, d, J = 6.1, CH(CH3)2), 2.26 (3H, s, ArCH3), 3.82 (3H, s, OCH3), 4.42 (1H, sept, J = 6.1, OCH), 6.72-6.94 (3H, m, ArH × 3)). An nuclear Overhauser enhancement (NOE) between methoxyl protons and aromatic protons was observed in the 1H-NMR spectrum of 13, while this NOE was negligible in the spectrum of 7.
- Gruter , G.-J. M. , Akkerman , O. S. and Bickelhaupt , F. 1994 . J. Org. Chem. , 59 : 4473 Direct bromination of 2,3-dimethoxytoluene using NBS in carbon tetrachloride or acetonitrile affording 6-bromo-2,3-dimethoxytoluene in high yield has been reported (see:
- Albrecht , M. 1996 . Synthesis , : 230
- Knölker , H.-J. and Fröhner , W. 1997 . Tetrahedron Lett. , 38 : 1535 However, the direct conversion of 7 to 10a under similar conditions was unsuccessful, and an inseparable mixture of 10a and 10b was obtained
- Banwell , M. G. , Flynn , B. L. and Stewart , S. G. 1998 . J. Org. Chem. , 63 : 9139
- Endo , A. , Kann , T. and Fukuyama , T. 1999 . Synlett. , : 1103 Since we completed this paper, selective protection of 2,3-dihydroxytoluene (4) by TsCl was reported by Fukuyama in his synthetic study on ecteinascidin: