Lithiation of 2-aryl-2-methyl-1,3-dioxolanes with PMDTA-complexed butyllithium

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• 作者：Bá ; lint Nyulasi^a ; Andrá ; s Né ; meth^a ; Má ; rta Porcs-Makkay^a ; Jó ; zsef Kupai^b ; Gyula Luká ; cs^a ; Gyula Simig^a ; Balá ; zs Volk^a ; ^{volk.balazs@egis.hu}
• 关键词：Metalation ; Lithiation ; Regioselectivity ; Acetophenone ketals ; Carboxylation
• 刊名：Tetrahedron
• 出版年：2017
• 出版时间：26 January 2017
• 年：2017
• 卷：73
• 期：4
• 页码：298-306
• 全文大小：785 K
• 卷排序：73

文摘

The metalation of chloro- and methoxy-substituted acetophenone ketals with butyllithium (BuLi) and with N,N,N′,N″,N″-pentamethyldiethylenetriamine-complexed butyllithium (BuLi/PMDTA) has been investigated. The lithio species thus generated were carboxylated to benzoic acids. Lithiations with BuLi occurred regioselectively ortho to the ketal substituent. When using BuLi/PMDTA, a regiodivergent behavior has generally been found in the lithiations. However, in some cases a significant selectivity was observed, enabling the preparation of the main regioisomer, exhibiting a new substitution pattern, with reasonable yield.