In this report, an unusual bond activation strategy has been demonstrated by BICAAC, which essentially emulates the behavior of a transition metal. The ambiphilic nature of this specific carbene has facilitated a simultaneous proton and hydride capture from an alcohol molecule to carry out smooth dehydrogenation under mild conditions. The activation route closely follows the traditional metal–ligand bifunctional activation of a substrate. The hydrogen molecule extracted from the substrate alcohol becomes stored in the carbene carbon, which has been unambiguously ascertained by the isolation of this intermediate and its X-ray crystallographic characterization. Such an event has further been interrogated in detail by the deuterium-labeling experiment and DFT computations to substantiate the critical role of carbene’s ambiphilicity. Additionally, the stored hydrogen in the carbene molecule has been delivered to an in situ-generated olefinic bond to completely mimic a borrowing hydrogen reaction in an organocatalytic fashion. Both dehydrogenation and rehydrogenation reactions have been conducted in a single pot using BICAAC as the catalyst that alkylates fluorene at its 9-position using a series of alcohols as the alkyl source. A thorough mechanistic sketch describes the involvement of a radical for the latter part of the reaction, overall bringing a different outlook to carbene-promoted small-molecule activation reactions.

中文翻译：

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通过 BICAAC 模拟金属-配体协同作用进行两亲醇脱氢

在本报告中，BICAAC 演示了一种不寻常的键激活策略，它本质上模拟了过渡金属的行为。这种特定卡宾的两亲性质促进了从醇分子中同时捕获质子和氢化物，从而在温和条件下顺利进行脱氢。激活途径与底物的传统金属-配体双功能激活密切相关。从底物醇中提取的氢分子储存在卡宾碳中，这一点已通过该中间体的分离及其 X 射线晶体学表征明确确定。氘标记实验和 DFT 计算进一步详细探讨了这一事件，以证实卡宾两亲性的关键作用。此外，卡宾分子中储存的氢已被传递至原位生成的烯键，以完全模拟有机催化方式的借氢反应。脱氢和再氢化反应均在单锅中进行，使用 BICAAC 作为催化剂，使用一系列醇作为烷基源将芴在其 9 位烷基化。完整的机理草图描述了反应后半部分自由基的参与，总体上为卡宾促进的小分子活化反应带来了不同的前景。