Regioselective Cleavage Reaction of the Aromatic Methylenedioxy Ring. V. Cleavage with Sodium Alkoxides - Alcohols, Potassium tert-Butoxide - Alcohols, Dimsyl Anion - Methyl Alcohol, Metallic Sodium - Alcohols, and Sodium Cyanide in Dipolar Aprotic Solvents.
作者:Yasuhiro IMAKURA、Kazuto OKIMOTO、Tatsuya KONISHI、Mariko HISAZUMI、Junyo YAMAZAKI、Shigeru KOBAYASHI、Shinsuke YAMASHITA
DOI:10.1248/cpb.40.1691
日期:——
The reaction of aromatic methylenedioxy compounds containing electron-withdrawing groups with dimsyl anion-methyl alcohol, potassium tert-butoxide-alcohols, and metallic sodium-alcohols in dimethyl sulfoxide (DMSO), and with sodium alkoxides-alcohols in hexamethylphosphoramide, gave 3- and 4-hydroxybenzene derivatives in good yield by regioselective attack of the alkoxide ions on the methylenedioxy ring. The formation mechanism of alkoxide ions and the effect of DMSO in the cleavage reaction of the methylenedioxy ring are discussed on the basis of proton nuclear magnetic resonance (1H-NMR) spectra. The reactions of aromatic methylenedioxy compounds (3 and 22) with sodium cyanide in dipolar aprotic solvents gave 4-cyano-3-hydroxybenzene derivatives (23 and 24) by regioselective attack of the cyanide ion on the methylenedioxy ring. The reactions of aromatic methylenedioxy compounds (28-30) containing no electron-withdrawing group with MeONa-MeOH in dipolar aprotic solvents gave non-regioselective cleavage products (31 and 34).
甲基二氧芳香族化合物与二甲基亚砜(DMSO)中的二甲基磺酸酯阴离子-甲醇、叔丁醇钾-醇以及金属钠-醇反应,以及与六甲基磷酰胺中的烷氧化钠-醇反应,通过烷氧化离子对甲基二氧环的选择性攻击,以良好的产率得到3-和4-羟基苯衍生物。根据质子核磁共振(1H-NMR)谱,讨论了烷氧化离子的形成机制以及DMSO对甲基二氧环裂解反应的影响。芳香族甲基二氧化合物(3和22)与氰化钠在偶极非质子溶剂中的反应,通过氰化物离子对甲基二氧环的选择性攻击,得到4-氰基-3-羟基苯衍生物(23和24)。不含吸电子基团的芳香族甲基二氧化合物(28-30)与甲醇钠-甲醇在偶极非质子溶剂中的反应,得到非选择性裂解产物(31和34)。