[C-H Functionalization by Transition-metal-catalyst or in Situ Generated Base].

Direct functionalization of the C-H bond is a highly attractive method because it does not require any pre-functionalized starting materials. Therefore this method can be adopted to attain the atom- and step-economic synthesis of organic compounds. We recently developed novel C-H functionalization reactions using two strategies. The first strategy is transition-metal catalyzed C-H functionalization, which comprises the copper-catalyzed oxidative C(sp3)-H functionalization of 2-alkyl-N-arylbenzamides for the synthesis of N-aryl-isoindolinones. This method can be applied to various substituted substrates and the synthesis of bioactive compounds, indoprofen and DWP205190. It provides an efficient approach toward the construction of isoindolinone skeletons. The second strategy is an in situ generated base-mediated C-H functionalization comprising the deprotonative silylation of C(sp)-H and C(sp2)-H bonds by the base generated in situ from trifluoromethyltrimethylsilane (CF3SiMe3) and its activator. In the C(sp)-H silylation of terminal alkynes, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) acts as both a solvent and activator; therefore no additional activator is required. Moreover, the preferential deprotonation of terminal alkynes using this system proceeds faster than the trifluoromethylation of ketones and esters.