Palladium-catalyzed direct 5-arylation of 1,3-dimethyluracil with aryl bromides: an electrophilic metalation–deprotonation with electrophilic arylpalladium intermediate
作者:Ko Hoon Kim、Hyun Seung Lee、Jae Nyoung Kim
DOI:10.1016/j.tetlet.2011.09.066
日期:2011.11
An efficient method of palladium-catalyzed direct 5-arylation of 1,3-dimethyluracil was developed with a various range of aryl bromides including electron-deficient aryl bromides. 5-Aryluracil derivatives were obtained in moderate to good yields regioselectively most likely via an electrophilic metalation–deprotonation process.
Switching the Regioselectivity of Direct C-H Arylation of 1,3-Dimethyluracil
作者:Miroslava Čerňová、Radek Pohl、Michal Hocek
DOI:10.1002/ejoc.200900586
日期:2009.8
An interesting dichotomy in the regioselectivity and mechanism of directC–Harylation of 1,3-dimethyluracil was observed. Its Pd-catalyzed reactions with diverse aryl halides in the absence of CuI lead preferentially to 5-aryluracils, while reactions in the presence of CuI give 6-aryl derivatives as the major products. Cu-mediated reactions (in the absence of a Pd catalyst) proceed with lower efficiency
Photolysis of5-bromo-1, 3-dimethyluracil (5-BDMU) in substituted benzenes afforded the corresponding 5-aryl derivatives together with the unexpected 6-isomers as an isomeric mixture. The 6-isomers were found to be derived from the protonated 5-BDMU, presumably via the interaction between LUMO5-BDMU (in the excited triplet state) and LUMOaryl (in the ground state).
PHOTOLYSIS OF 5-BR0M0-1,3-DIMETHYLURACIL IN SUBSTITUTED BENZENES
作者:Koh-ichi Seki、Yuko Bando、Kazue Ohkura
DOI:10.1246/cl.1986.195
日期:1986.2.5
Photolysis of 5-bromo-1,3-dimethyluracil in toluene, xylene and anisole afforded the anormalously substituted 6-aryl-1,3-dimethyluracils beside the expected products 5-aryl-1,3-dimethyluracils, while the reaction with veratrole occurred exclusively at the 5-position of the uracil ring.