Cycloaddition Across the Benzofuran Ring as an Approach to the Morphine Alkaloids

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• 作者：Stefan France ; Jutatip Boonsombat ; Carolyn A. Leverett ; Albert Padwa
• 刊名：Journal of Organic Chemistry
• 出版年：2008
• 出版时间：October 17, 2008
• 年：2008
• 卷：73
• 期：20
• 页码：8120-8123
• 全文大小：177K
• 年卷期：v.73,no.20(October 17, 2008)
• ISSN：1520-6904

文摘

The intramolecular Diels−Alder reaction of several amidofurans tethered onto a benzofuran ring was examined as a strategy for the synthesis of morphine. Bromo substitution on the furan ring did not provide sufficient activation to allow the cycloaddition to take place across the aromatic benzofuran. However, the presence of a large o-methylbenzyl group on the amido nitrogen atom causes the reactive s-trans conformation of the amidofuran to be highly populated, thereby facilitating its Diels−Alder cycloaddition across a tethered benzofuran.