We have developed a modular procedure to synthesize allylic alcohols from tertiary, secondary, and primary alkyl halides and alkynes via a Cu-catalyzed hydrocarbonylative coupling and 1,2-reduction tandem sequence. The use of tertiary alkyl halides as electrophiles was found to enable the synthesis of various allylic alcohols bearing α-quaternary carbon centers in good yield with high 1,2-reduction selectivity. Mechanistic studies that suggested a different pathway was operative with tertiary alkyl halides compared with primary and secondary alkyl halides for generating the key copper(III) oxidative adduct. For tertiary electrophiles, an acyl halide likely forms via radical atom transfer carbonylation. The preference for 1,2-reduction over 1,4-reduction of α,β-unsaturated ketones bearing tertiary substituents was rationalized using density functional theory transition state analysis. On the basis of this computational model, the coupling method was extended to primary and secondary alkyl iodide electrophiles by using internal alkynes with aryl substituents, providing trisubstituted allylic alcohols in high yield with good regioselectivity.

中文翻译：

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Cu催化炔烃与卤代烃的烃基化偶联合成烯丙醇

我们开发了一种模块化程序，通过 Cu 催化的烃化偶联和 1,2-还原串联序列从叔、仲和伯烷基卤化物和炔烃合成烯丙醇。发现使用叔烷基卤化物作为亲电子试剂能够以高产率和高 1,2-还原选择性合成各种带有 α-季碳中心的烯丙醇。机理研究表明，与伯和仲烷基卤化物相比，叔烷基卤化物可通过不同的途径产生关键的铜 (III) 氧化加合物。对于叔亲电试剂，酰基卤可能通过自由基原子转移羰基化形成。对 α 的 1,2-减少比 1,4-减少的偏好，使用密度泛函理论过渡态分析使带有叔取代基的 β-不饱和酮合理化。在该计算模型的基础上，通过使用带有芳基取代基的内炔，将偶联方法扩展到伯和仲烷基碘化物亲电试剂，以高产率提供具有良好区域选择性的三取代烯丙醇。