An Immobilized‐Dirhodium Hollow‐Fiber Flow Reactor for Scalable and Sustainable C−H Functionalization in Continuous Flow

Abstract

A scalable flow reactor is demonstrated for enantioselective and regioselective rhodium carbene reactions (cyclopropanation and C-H functionalization) by developing cascade reaction methods employing a microfluidic flow reactor system containing immobilized dirhodium catalysts in conjunction with the flow synthesis of diazo compounds. This allows the utilization of the energetic diazo compounds in a safe manner and the recycling of the dirhodium catalysts multiple times. This approach is amenable to application in a bulk-scale synthesis employing asymmetric C-H functionalization by stacking multiple fibers in one reactor module. The products from this sequential flow-flow reactor are compared with a conventional batch reactor or flow-batch reactor in terms of yield, regioselectivity, and enantioselectivity.

Pushing the boundaries of C–H bond functionalization chemistry using flow technology

“…After 10 consecutive runs with the same immobilized catalyst to couple 4-methoxytoluene and hydrazone, the yield was only slightly lower, dropping from 74% to 65%, while the enantioselectivity remained unchanged (89 to 86% ee). These results are comparable with the results obtained for the homogeneous catalyst under batch conditions [47]. ) is a useful photocatalyst for the direct activation of hydridic C − H bonds through hydrogen atom transfer (simultaneous abstraction of a proton and an electron).…”

Synthetic Exploration of α‐Diazo γ‐Butyrolactams

“…α‐Diazo monocarbonyl compounds have attracted considerable attention due to their high reactivity and wealth of possible synthetic transformations . Today, however, certain such compounds remain poorly explored.…”

Photoinduced Heterogeneous C−H Arylation by a Reusable Hybrid Copper Catalyst

“…[13] In spite of notablep rogress, photoinduced organo-metallicC ÀHactivations were thus far limitedt ohomogeneous catalysis, often leading to undesired trace metal impurities in the target products,a nd, more importantly,i nherently preventing catalysts from reuse. [14] Although selecteds ilica-supported catalysts [15] with non-excited-state reactivity were elegantly developed by Jones/Davies [16] andS awamura, [17] heterogeneous catalysisf or photoinduced CÀHa ctivation has thus far unfortunatelyp rovenelusive. [a] I.…”