The generation and reactivity of two model vinyl carbenoids from gem-dibromoalkenes 1 were studied in microflow systems. From substrate 1a (R = Ph, CF₃), the lithium-bromine exchange could be simply performed within 30 ms at 20 °C with very good E-selectivity whereas the reaction was unselective under batch conditions, even at −78 °C. Moreover, the unstable carbenoid generated from 1b (R = Ph, H) could be trapped as the major product while only the Fritsch-Buttemberg-Wiechell rearrangement product was obtained in a flask under cryogenic conditions.

Graphical abstract

中文翻译：

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宝石-二溴烯烃上的溴-锂交换第1部分：批次与微流条件

在微流系统中研究了两种来自宝石-二溴烯烃1的模型乙烯基类胡萝卜素的生成和反应性。从底物1a（R = Ph，CF ₃），锂-溴交换可以简单地在20 ms的30毫秒内以非常好的E选择性进行，而在间歇条件下，即使在-78°C，反应也是非选择性的。此外，从1b（R = Ph，H）生成的不稳定类胡萝卜素可以被捕集为主要产物，而在低温条件下只能在烧瓶中获得Fritsch-Buttemberg-Wiechell重排产物。

图形概要