Highly Stereoselective Chemoenzymatic Synthesis of the 3H-Isobenzofuran Skeleton. Access to Enantiopure 3-Methylphthalides

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• 作者：Juan Mangas-S谩nchez ; Eduardo Busto ; Vicente Gotor-Fern谩ndez ; Vicente Gotor
• 刊名：Organic Letters
• 出版年：2012
• 出版时间：March 16, 2012
• 年：2012
• 卷：14
• 期：6
• 页码：1444-1447
• 全文大小：233K
• 年卷期：v.14,no.6(March 16, 2012)
• ISSN：1523-7052

文摘

A straightforward synthesis of (S)-3-methylphthalides has been developed, with the key asymmetric step being the bioreduction of 2-acetylbenzonitriles. Enzymatic processes have been found to be highly dependent on the pH value, with acidic conditions being required to avoid undesired side reactions. Baker鈥檚 yeast was found to be the best biocatalyst acting in a highly stereoselective fashion. The simple treatment of the reaction crudes with aqueous HCl has provided access to enantiopure (S)-3-methylphthalides in moderate to excellent yields.