Application of organolithium and related reagents in synthesis. Part 25: Novel specific synthesis of the 4-arylisochroman-3-acetic acids via conversion of benzoic acids

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• 作者：Bieniek ; Adam ; Epsztajn ; Jan ; Kowalska ; Justyna A. ; Malinowski ; Zbigniew
• 关键词：benzanilides ; metallations ; isochromans
• 刊名：Tetrahedron Letters
• 出版年：2001
• 出版时间：December 24, 2001
• 年：2001
• 卷：42
• 期：5
• 页码：9293-9295
• 全文大小：79.6 K

文摘

The transformation of the benzanilides 1 into 4-arylisochroman-3-acetic acids 8 applying the following sequence of reactions is described. At first, the 3-arylphthalides 3 were obtained via metallation [n-BuLi] of benzanilides 1 and subsequent treatment of the generated bis-lithiated anilides 2 with aromatic aldehydes. Next, the 3-arylphthalides 3 were reduced [LiBH₄] to phthalanes 5 and then, via reductive metallation [Li/C₁₀H₈] and reaction of the generated bis-lithiated species 6 with dimethylformamide, 3-hydroxy-4-arylisochromans 7 were produced. In the final step the isochromans 7 were treated with 1-methoxy-1-trimethylsilyloxyethene in the presence of titanium tetrachloride and furnished 4-arylisochromans-3-acetic acid methyl esters 8 as trans stereoisomers (Ψ-e/e).