Papidocha Sven M, Carreira Erick M
Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zürich, Zürich 8093, Switzerland.
J Am Chem Soc. 2024 Aug 28;146(34):23674-23679. doi: 10.1021/jacs.4c07690. Epub 2024 Aug 19.
The installation of vicinal quaternary centers with absolute stereocontrol constitutes a considerable challenge in organic synthesis. Herein, we introduce a novel [Cp*Ru(MeCN)]PF/phenoxythiazoline catalyst system that achieves enantiospecific allylic substitution of tertiary carbonates with α,α-disubstituted lithium ester enolates to give products containing vicinal quaternary centers. Noteworthy features include the direct use of nonstabilized ester enolates, a class of nucleophiles which has rarely been used in transition metal-catalyzed allylic substitution reactions. The approach is demonstrated for a broad scope of tertiary electrophiles as well as ester enolates and accomplishes stereoretentive substitution with excellent conservation of ee (89-99%) and branched/linear regioselectivities (up to 40:1).
在有机合成中，构建具有绝对立体控制的邻位季碳中心是一项极具挑战性的任务。在此，我们介绍了一种新型的[Cp*Ru(MeCN)]PF/苯氧基噻唑啉催化剂体系，该体系可实现叔碳酸酯与α,α-二取代锂酯烯醇盐的对映体特异性烯丙基取代反应，从而得到含有邻位季碳中心的产物。值得注意的特点包括直接使用未稳定化的酯烯醇盐，这是一类在过渡金属催化的烯丙基取代反应中很少使用的亲核试剂。该方法适用于多种叔亲电试剂以及酯烯醇盐，并实现了立体保持取代反应，具有出色的对映体过量（ee）保留率（89-99%）和支链/直链区域选择性（高达40:1）。
