Trifunctionalization of Aryl Iodides with Two Distinct Nitrogen and Carbon Electrophiles by Palladium/Norbornene Catalysis

Abstract

Main observation and conclusion Herein, we report a highly chemo‐ and regioselective vicinal trifunctionalization of aryl iodides by palladium/norbornene (Pd/NBE) catalysis. The key feature of this new method is the introduction of two distinct nitrogen and carbon electrophiles, with a large gap in reactivity, for ortho‐unsubstituted aryl iodides via an intermolecular and intramolecular C―H functionalization, respectively. Eight types of ipso terminations can be coupled with both ortho‐amination and ortho‐alkylation, affording a variety of polysubstituted benzoheterocyclic scaffolds. Silicon‐tethered substrates can lead to polyfucntional arenes via a single‐step operation. Noteworthy, these products exhibit full‐color‐tunable strong fluorescence emissions with large Stokes shifts, and product 7r can serve as a fluorescent probe to specifically target lysosome in living cells.

Trifunctionalization of aryl iodides via intermolecular C–H acylation/intramolecular C–H alkylation achieved using palladium/norbornene cooperative catalysis

“…12f As a result, we obtained good yields of various interesting polycyclic frameworks, such as dihydrobenzofuran (7), lactone (8), and iso-indolinones (9 and 10). Furthermore, products 4a and 4f were, by being each subjected to oxidative treatment, easily converted into benzofuran (11) and indole (12) (Scheme 3C).…”

“…Based on previous reports, 8–11 a catalytic cycle was proposed and is outlined in Scheme 4. According to this proposal, oxidative addition of Pd(0) to the aryl iodide 1a followed by norbornene insertion gives complex B .…”

“…With our continued interest in Catellani-type trifunctionalization and inspired by a tethering strategy developed by Lautens and colleagues, 9,10 we made progress on the Pd/NBE-catalyzed trifunctionalization of aryl iodides, where the combination of electrophiles could be extended to two distinct nitrogen and carbon electrophiles having highly disparate reactivities (Scheme 1B, iii). 11 Motivated by the aforementioned studies, we set out to enhance the selectivity for trifunctionalization with alkyl and acyl electrophiles by tethering an alkyl electrophile on aryl iodides (Scheme 1B, iv). Herein, we report a new Pd/NBE-catalyzed trifunctionalization reaction based on a highly chemoselective cascade process involving intermolecular ortho acylation/intramolecular ortho alkylation/ ipso alkenylation.…”

Palladium-catalyzed triple coupling of 2-iodoanisoles with aryl iodides to access 6H-dibenzopyrans

“…As a class of important palladacycles, C,C-palladacycles are usually utilized to develop new transformations. In the widely studied Catellani reaction, 4 norbornene or its analogues was used as a mediator to generate the C,C-palladacycle. In addition, other methods of producing C,C-palladacycles and the related transformations have been extensively studied.…”