TY  - JOUR
A1  - Riemer, Nastja
A1  - Shipman, Michael
A1  - Wessig, Pablo
A1  - Schmidt, Bernd
T1  - Iterative arylation of itaconimides with diazonium salts through electrophilic palladium catalysis
BT  - divergent beta-H-Elimination pathways in repetitive Matsuda-Heck reactions
JF  - The journal of organic chemistry
N2  - N-Arylitaconimides, accessible from maleic anhydride, anilines, and paraformaldehyde, react with arene diazonium salts in Pd-catalyzed Matsuda-Heck arylation to the pharmacologically relevant E-configured 3-arylmethylidene pyrrolidine-2,5-diones (also known as arylmethylidene succinimides) through exo-selective beta-H-elimination. The coupling proceeds at ambient temperature with the simple and easy-to-handle precatalyst Pd-II-acetate under ligandand base-free conditions. Notable features are high isolated yields, regio- and stereoselectivities, and short reaction times. In a comparative investigation, aryl iodides, bromides, and triflates were shown to be inferior coupling reagents in this reaction. The 3-arylmethylidene pyrrolidine-2,5-diones undergo second Matsuda-Heck coupling, which proceeds via endo-selective beta-H-elimination to give diarylmethyl-substituted maleimides as coupling products. These products can also be accessed in one flask by sequential addition of different arene diazonium salts to the starting itaconimide. The potential of 3-arylmethylidene succinimides as photoswitches was tested. Upon irradiation of the E-isomer at 300 nm, partial isomerization to the Z-isomer (E/Z = 65:35 in the photostationary state) was observed. The isomerization was found to be nearly completely reversible by irradiating the mixture at 400 nm.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.joc.9b00627
SN  - 0022-3263
VL  - 84
IS  - 9
SP  - 5732
EP  - 5746
PB  - American Chemical Society
CY  - Washington
ER  -