Suzuki-Miyaura Coupling Enabled by Aryl to Vinyl 1,4-Palladium Migration

Abstract

The Suzuki-Miyaura coupling is a fundamentally important transformation in modern organic synthesis. The development of new reaction modes for new chemical accessibility and higher synthetic efficiency is still the consistent pursuance in this field. An efficient Suzuki-Miyaura coupling enabled by a controllable 1,4-palladium migration was realized to afford stereodefined multisubstituted olefins and 1,3-dienes. The reaction exhibits remarkable broad substrate scope, excellent functional-group tolerance, versatile conversion with obtained products, and easy scalability. The practicality of this method is highlighted by the aggregation-induced emission feature of the produced olefins and 1,3-dienes, as well as the capability of affording geometric isomer pairs with a marked difference on photoluminescent quantum yield values.

Innovative Synthetic Procedures for Luminogens Showing Aggregation‐Induced Emission

“…Very recently,a ni nteresting Suzuki-Miyaura coupling enabled by ac ontrollable 1,4-palladium migration to afford olefins 1 and 1,3-dienes 2 with multiple aryl substituents was reported (Figure 3A). [29] An initial oxidative addition of ortho-vinylbromobenzene to palladium(0) generates the intermediate 1/2 I,a fter which aconcerted metalation-deprotonation (CMD) process and 1,4-palladium migration occur consecutively with the formation of intermediate 1/2 II.T he desired products are finally generated through subsequent Suzuki coupling sequences.S ome of the products exhibited typical AIE characteristics.O lefin 1a emitted very low fluorescence at low concentration in THF solutions,w hereas the nanoaggregates were brightly emissive.T he photoluminescence (PL) was further studied in am ixture of THF/H 2 O. As shown in Figure 3B,c ontinuously increasing the water fraction to 90 %led to agradual enhancement of the luminescence intensity,t hus demonstrating aprominent AIE effect.…”

“…Very recently, an interesting Suzuki–Miyaura coupling enabled by a controllable 1,4‐palladium migration to afford olefins 1 and 1,3‐dienes 2 with multiple aryl substituents was reported (Figure 3 A). [29] An initial oxidative addition of ortho ‐vinylbromobenzene to palladium(0) generates the intermediate 1/2 I , after which a concerted metalation‐deprotonation (CMD) process and 1,4‐palladium migration occur consecutively with the formation of intermediate 1/2 II . The desired products are finally generated through subsequent Suzuki coupling sequences.…”

A 1,4‐Palladium Migration/Heck Sequence with Unactivated Alkenes: Stereoselective Synthesis of Trisubstituted 1,3‐Dienes

“…Recently, we [9] and others [10] have demonstrated aryl to alkenyl 1,4‐palladium migration as a powerful method for generation of stereodefined alkenyl palladium species which were applied to some stereoselective cascade reactions with unsaturated carbony compounds, [9c] aryl or alkenyl boronic esters, [9a] 1,3‐diene [9b] et al . We wondered if an unactivated olefin was involved in a 1,4‐Pd migration/Heck sequence (Scheme 1c), it would provide a new route to the challenging triaryl‐substituted 1,3‐dienes.…”

Innovative Verfahren zur Synthese von Luminogenen mit aggregationsinduzierter Emission

“…Erst kürzlich wurde über eine interessante Suzuki‐Miyaura‐Kupplung berichtet, die durch eine steuerbare 1,4‐Wanderung von Palladium ermöglicht wurde und mit mehreren Arylresten substituierte Olefine 1 und 1,3‐Diene 2 lieferte (Abbildung 3 A). [29] Durch oxidative Addition von o ‐Bromvinylbenzol an Palladium(0) entsteht zunächst das Zwischenprodukt 1 / 2 I ; danach finden aufeinanderfolgend eine konzertierte Metallierung‐Deprotonierung (CMD, concerted metalation‐deprotonation) und eine 1,4‐Wanderung von Palladium statt, wodurch das Zwischenprodukt 1 / 2 II gebildet wird. Die gewünschten Produkte werden schließlich durch die nachfolgende Sequenz von Suzuki‐Kupplungen gebildet.…”