A direct conversion of C(sp(3))-H bonds to C(sp(3))-F bonds has been developed. In this process, a catalytic N-oxyl radical generated from N,N-dihydroxypyromellitimide abstracts hydrogen from the C(sp(3))-H bond and Selectfluor acts to trap the resulting carbon radical to form the C(sp(3))-F bond. This simple metal-free protocol enables the chemoselective introduction of a fluorine atom into various aromatic and aliphatic compounds and serves as a powerful tool for the efficient synthesis of fluorinated molecules.
A direct conversion of C(sp(3))-H bonds to C(sp(3))-N bonds has been achieved by utilizing catalytic N-hydroxyphthalimide (NHPI) and stoichiometric dialkyl azodicarboxylate. NHPI functions as a precursor of the electron-deficient phthalimide N-oxyl radical (PINO) to abstract hydrogens, and dialkyl azodicarboxylate acts as a trapping agent of the resultant carbon radical to generate the hydrazine derivatives. This C-H amination proceeds in a highly chemoselective manner with a wide applicability to functionalize benzylic, propargylic, and aliphatic C-H bonds. Furthermore, the obtained hydrazine compounds were readily converted to the corresponding carbamates or amines. Hence, the present protocol for direct introduction of the nitrogen functionality serves as a powerful tool for efficient construction of nitrogen-substituted natural products and pharmaceuticals.
The simple reagent system composed of NDHPI (cat.) and Selectfluor enables a metal-free fluorination under mild conditions. The reaction features predictable chemoselectivity towards the benzylic or the tertiary position of the aromatic or aliphatic substrates respectively, along with high tolerance to various functionalities. -(AMAOKA, Y.; NAGATOMO, M.; INOUE*, M.; Org. Lett. 15 (2013) 9, 2160-2163, http://dx.doi.org/10.1021/ol4006757 ; Grad. Sch. Pharm. Sci., Univ. Tokyo, Bunkyo, Tokyo 113, Japan; Eng.) -M. Duhs 35-029
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.