- Selective Preparation. 37. Bromination of 2,2',-Dihydoxy-3,3',5,5'-tetra-tert-butylbiphenyl and Preparation of Hydroxydibenzofurans
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Treatment of 2,2'-dihydroxy-3,3',5,5'-tetra-tert-butylbiphenyl (3) with excess bromine in alcohols afforded the 2-alkoxy-1-bromo-4,6,8-tri-tert-butyldibenzofurans 6a,b in 68 percent and 44 percent yields, respectively.When compound 6a was treated with AlCl3 in boiling toluene, 2-hydroxydibenzofuran (14) was obtained in 79 percent yield together with bromotoluenes (15) and tert-butyltoluenes (10).However, at room temperature, this reaction afforded 1-bromo-2-methoxy-4-tert-butyldibenzofuran (16) in 74 percent yield.Futhermore, it was found that AlCl3-CH3NO2-catalyzed reaction of 6a in toluene gave 1-bromo-2-methoxy-4,6-di-tert-butyldibenzofuran (17) in 71 percent yield together with 10.From 6a were obtained 1,2,8-trihydroxy-(26) and 1,2,7,8-tetrahydroxydibenzofuran (27) in several steps.
- Tashiro, Masashi,Yoshiya, Haruo,Fukata, Gouki
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p. 4425 - 4429
(2007/10/02)
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- A CONVENIENT PREPARATION OF 2-HYDROXYDIBENZOFURAN FROM 2,2'-DIHYDROXY-3,3',5,5'-TETRA-TERT-BUTYLBIPHENYL IN TWO STEPS
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Bromination of 2,2'-dihydroxy-3,3',5,5'-tetra-tert-butylbiphenyl (2) with bromine in alcohols such as methanol and ethanol afforded the corresponding 1-bromo-2-alkoxy-4,5,7-tri-tert-butyldibenzofurans (5).The AlCl3 catalyzed reaction of 5a (R = CH3) in boiling toluene gave 2-hydroxydibenzofuran (7) in 79percent yield.The mechanism of the formation of 5 from 2 was also discussed.
- Tashiro, Masashi,Yoshiya, Haruo,Fukata, Gouki
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p. 1955 - 1958
(2007/10/02)
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