Abstract

The enantioselective organocatalytic reduction of aryl-substituted nitroenamines was successfully performed under continuous-flow conditions. After a preliminary screening with a 10-μL microreactor, to establish the best reaction conditions, the reduction was scaled up in a 0.5-mL mesoreactor, without appreciable loss of enantioselectivity, that remained constantly higher than 90%. The in-flow nitro reduction was also accomplished, either by Raney nickel catalyzed hydrogenation or by a metal-free methodology based on the use of the very inexpensive and readily available reducing agent trichlorosilane. The final aim is to develop a two-step, continuous-flow process for the stereo­selective, metal-free, catalytic synthesis of differently functionalized chiral 1,2-diamines.

The enantioselective organocatalytic reduction of aryl-substituted nitroenamines was successfully performed under continuous-flow conditions. After a preliminary screening with a 10-μL microreactor, to establish the best reaction conditions, the reduction was scaled up in a 0.5-mL mesoreactor, without appreciable loss of enantioselectivity, that remained constantly higher than 90%. The in-flow nitro reduction was also accomplished, either by Raney nickel catalyzed hydrogenation or by a metal-free methodology based on the use of the very inexpensive and readily available reducing agent trichlorosilane. The final aim is to develop a two-step, continuous-flow process for the stereo­selective, metal-free, catalytic synthesis of differently functionalized chiral 1,2-diamines.

中文翻译：

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一种连续流动，两步，无金属的方法，用于合成不同取代的手性1,2-二氨基衍生物

摘要

在连续流动条件下成功进行了对芳基取代的亚硝基胺的对映选择性有机催化还原。在使用10μL微型反应器进行初步筛选以建立最佳反应条件后，在0.5 mL中反应器中按比例放大还原反应，而对映选择性没有明显损失，且始终高于90％。还可以通过阮内镍催化的氢化或通过基于使用非常便宜且容易获得的还原剂三氯硅烷的无金属方法来实现流中硝基还原。最终目的是开发一种两步连续流方法，用于不同功能化的手性1,2-二胺的立体选择性，无金属催化合成。

在连续流动条件下成功进行了对芳基取代的亚硝基胺的对映选择性有机催化还原。在使用10μL微型反应器进行初步筛选以建立最佳反应条件后，在0.5 mL中反应器中按比例放大还原反应，而对映选择性没有明显损失，且始终高于90％。还可以通过阮内镍催化的氢化或通过基于使用非常便宜且容易获得的还原剂三氯硅烷的无金属方法来实现流中硝基还原。最终目的是开发一种两步连续流方法，用于不同功能化的手性1,2-二胺的立体选择性，无金属催化合成。