Trimethyl orthoacetate as a convenient reagent for selective methylation of β-OH groups of (poly)hydroxynaphthazarins
Trimethyl orthoacetate was found to be a convenient reagent for methylation of the β-OH groups of (poly)hydroxynaphthazarins. The substrates bearing one β-OH group react with MeC(OMe)3 to give the corresponding methoxy derivatives in 79–89% yields. Depending on the reaction conditions, methylation of substrates with two β-OH groups on the different and the same rings affords either the corresponding mono-O-methylated (43–70%) or di-Omethylated (71–78%) derivatives. Trimethyl orthoacetate offers a good alternative to CH2N2 in the preparative synthesis of O-methylated (poly)hydroxynaphthazarin derivatives.
Balaneva,Shestak,Novikov
p. 55 - 63
(2019/04/25)
First direct observation of tautomerism of monohydroxynaphthazarins by IR-spectroscopy
Some substituted monohydroxylated naphthazarins (5,8-dihydroxy-l,4-naphthoquinones) were synthesized and studied by IR-spectroscopy in aprotic organic solvents at ambient temperature. Two narrow stretching mode bands in the high frequency range 3540-3410
Glazunov, Valery P.,Tchizhova, Alla Ya.,Pokhilo, Nataly D.,Anufriev, Victor Ph.,Elyakov, George B.
p. 1751 - 1757
(2007/10/03)
Chemistry of naphthazarin derivatives 8. Determination of structures of substituted 2-hydroxy-6(7)-methoxynaphthazarins and 7(8)-hydroxypyranonaphthazarins by IR spectroscopy
A set of substituted 2-hydroxy-6(7)-methoxynaphthazarins and 7(8)-hydroxypyranonaphthazarins were synthesized. The IR spectra of 2-hydroxy-6-methoxynaphthazarins and 7-hydroxypyranonaphthazarins, on the one hand, and of 2-hydroxy-7-methoxynaphthazarins an
Glazunov,Tchizhova,Shestak,Sopel'nyak,Anufriev
p. 95 - 100
(2007/10/03)
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