Liu Dongning, Bauer Nicola, Lu Wen, Yang Xiaoxiao, Wang Binghe
Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30303, United States.
J Org Chem. 2024 Jul 5;89(13):9551-9556. doi: 10.1021/acs.joc.4c00936. Epub 2024 Jun 18.
Because of endogenous signaling roles of carbon monoxide (CO) and its demonstrated pharmacological effects, there has been extensive interests in developing fluorescent CO probes. Palladium-mediated CO insertion has been successfully used for such applications. However, recent years have seen many publications of using uncatalyzed CO insertion into a hydrazone double bond as a way to sense CO. Such chemistry has no precedents otherwise. Further, the rigor of the CO-sensing work was largely based on using ruthenium-carbonyl complexes such as CORM-3 as CO surrogates, which have been reported to have extensive chemical reactivity and to release largely CO instead of CO unless in the presence of a strong nucleophile such as dithionite. For all of these, it is important to reassess the feasibility of such a CO-insertion reaction. By studying two of the reported "CO probes" using CO gas, this study finds no evidence of CO insertion into a hydrazone double bond. Further, the chemical reaction between CO gas and a series of eight hydrazone compounds was conducted, leading to the same conclusion. Such findings are consistent with the state-of-the-art knowledge of carbonylation chemistry and do not support uncatalyzed CO insertion as a mechanism for developing fluorescent CO probes.
由于一氧化碳（CO）的内源性信号传导作用及其已证实的药理作用，人们对开发荧光CO探针产生了广泛兴趣。钯介导的CO插入已成功用于此类应用。然而，近年来有许多关于利用未催化的CO插入腙双键作为检测CO的方法的报道。否则这种化学方法并无先例。此外，CO传感工作的严谨性很大程度上基于使用钌羰基配合物如CORM-3作为CO替代物，据报道这些配合物具有广泛的化学反应性，并且除非在存在强亲核试剂如连二亚硫酸盐的情况下，否则主要释放的不是CO而是其他物质。基于所有这些情况，重新评估这种CO插入反应的可行性很重要。通过使用CO气体研究两种已报道的“CO探针”，本研究未发现CO插入腙双键的证据。此外，进行了CO气体与一系列八种腙化合物之间的化学反应，得出了相同的结论。这些发现与羰基化化学的最新知识一致，不支持未催化的CO插入作为开发荧光CO探针的机制。
