Electrophilic Etherification of α-Heteroaryl Carbanions with Monoperoxyacetals as a Route to Ketene O,O- and N,O-Acetals,The Journal of Organic Chemistry

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Electrophilic Etherification of α-Heteroaryl Carbanions with Monoperoxyacetals as a Route to Ketene O,O- and N,O-Acetals
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2021-01-19 , DOI: 10.1021/acs.joc.0c02506
Timothy J Paris ₁ , Chris Schwartz ₁ , Rachel Willand-Charnley ₁

Affiliation

Alkyl ketene acetals are useful reactants in a variety of synthetic processes, and yet, there are limited routes to their formation as isolable products. We now report the successful synthesis and isolation of heteroaryl ketene acetals through intermolecular transfer of alkoxyl (δ⁺OR) from electrophilic peroxides to lithiated benzofurans, indoles, and pyridines. Primary and secondary peroxyacetals enable selective transfer of the nonanomeric alkoxy group in moderate to high yield; substrates bearing an electron-donating substituent show enhanced reactivity toward electrophilic oxygen. Heteroaryl ketene acetals are remarkably stable throughout traditional purification techniques; the superior stability of ketene N,O-acetals compared to ketene O,O-acetals is presumably due to increased aromaticity of the indole and pyridine structures. The presented method overcomes typical problems associated with alkyl ketene acetal synthesis as reported products withstood workup and flash column chromatography procedures.

中文翻译：

α-杂芳基碳负离子与单过氧缩醛的亲电醚化反应，可合成烯酮O，O-和N，O-缩醛

烷基烯酮缩醛在各种合成过程中都是有用的反应物，然而，形成可分离产物的途径有限。现在，我们报告了烷氧基（δ ⁺ OR）从亲电子过氧化物分子间转移到锂化苯并呋喃，吲哚和吡啶的成功合成和杂芳基乙烯酮缩醛的分离。伯和仲过氧缩醛能够以中等至高收率选择性转移非端基烷氧基。带有给电子取代基的底物对亲电子氧的反应性增强。在整个传统纯化技术中，杂芳基乙烯酮缩醛非常稳定。与乙烯酮O相比，乙烯酮N，O-缩醛的稳定性更高，O-缩醛大概是由于吲哚和吡啶结构的芳香性增加。提出的方法克服了与烷基烯酮缩醛合成相关的典型问题，因为所报道的产物经受了后处理和快速柱色谱程序。

更新日期：2021-02-05

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