Cp2TiCl2-Catalyzed Reductive Methylidenation of Alkyl Ketones with CH2Br2

IF 13.6 1区化学 Q1 CHEMISTRY, PHYSICAL

ACS Catalysis Pub Date : 2026-10-16 Epub Date: 2026-09-25 DOI:10.1021/acscatal.6c06010

Jieping Chen, Shannon S. Stahl

引用次数: 0

Abstract

Direct methylidenation of carbonyl compounds represents an appealing route to terminal alkenes. Existing methods for this transformation typically rely on stoichiometric phosphorus ylides (methylene Wittig) or organotitanium complexes (Tebbe or Petasis reagents). Here, we report a Cp₂TiCl₂-catalyzed method that uses CH₂Br₂ as a readily available carbene precursor and Zn as the reductant for methylidenation of alkyl ketones. The reaction is proposed to proceed via the in situ generation of an alkyl–Zn species, which then generates a Ti–carbene intermediate. Alkali metal salts, such as KBF₄ and LiPF₆, improve the reaction efficiency. Cyclic voltammetry studies implicate the alkali metal ions in promoting dissociation of chloride from Ti and enhancing reactivity with the alkyl–Zn reagent. The resulting protocol is operationally simple and offers a practical alternative to the use of stoichiometric methylidenation reagents.

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cp2ticl2催化烷基酮与CH2Br2的还原甲基化反应

羰基化合物的直接甲基化反应是生成末端烯烃的一种有吸引力的途径。这种转化的现有方法通常依赖于化学计量磷酰化物（亚甲基Wittig）或有机钛配合物（Tebbe或Petasis试剂）。在这里，我们报道了一种cp2ticl2催化的方法，该方法使用CH2Br2作为易于获得的碳前体，Zn作为烷基酮甲基化的还原剂。该反应建议通过原位生成烷基- zn，然后生成Ti-carbene中间体来进行。碱金属盐如KBF4和LiPF6提高了反应效率。循环伏安法研究表明，碱金属离子促进氯离子与钛的解离，并增强与烷基锌试剂的反应活性。由此产生的方案操作简单，并提供了一个实际的替代使用的化学计量甲基化试剂。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Catalysis CHEMISTRY, PHYSICAL-

CiteScore

20.80

自引率

6.20%

发文量

1253

审稿时长

1.5 months

期刊介绍： ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels. The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.