An
iodine-catalyzed Ritter-type amination of nonactivated C–H
bonds is presented enabling the formation of 1,3-α-tertiary
diamines. A sulfamidyl radical serves as the promoter in a guided
tertiary C–H iodination through an exclusive 1,6-HAT process.
The subsequent Ritter reaction furnishes the C–N bond and establishes
an unprecedented concept for catalyst turnover in iodine redox catalysis.
The general robustness of the methodology, including broad functional
group tolerance, was demonstrated for 24 different 1,3-diamine derivatives,
which were synthesized in yields of 42%–99%.
An innovative approach to position-selective polyhalogenation of aliphatic hydrocarbon bonds is presented. The reaction proceeded within the Hofmann-Löffler manifold with amidyl radicals as the sole mediators to induce selective 1,5- and 1,6-hydrogen-atom transfer followed by halogenation. Multiple halogenation events of up to four innate C-H bond functionalizations were accomplished. The broad applicability of this new entry into polyhalogenation and the resulting synthetic possibilities were demonstrated for a total of 27 different examples including mixed halogenations.
Lipophilic difluoromethyl-substituted cinnamic esters retain radical scavenging capabilities that prove useful to confer antioxidant properties in a non-polar environment.
Series of novel amides of isoferulic acid, where the phenolic hydroxyl was replaced by a difluoromethyl group, were synthesized and their in vitro antibacterial activities assayed against fourteen bacterial strains (six Gram-positive and eight Gram-negative). A one-pot methodology was developed to obtain the 3′-(difluoromethyl)-4′-methoxycinnamoyl amides using Deoxofluor® as a fluorinating agent. The N-isopropyl, N-isopentyl, and N-(2-phenylethyl) amides 11b, 11d and 11g were the most active and selective against Mycobacterium smegmatis (MIC = 8 µg/mL) with 11b and 11g displaying negligible or no cytotoxicity against HepG2 and A549 cells. Thirteen analogs of N-isopropylamide 11b were also synthesized and their antibacterial activity assayed. Results show that the difluoromethyl moiety enhanced antibacterial activity and selectivity towards M. smegmatis, changing the microorganism inhibition profile of the parent compound. The selectivity exhibited by some of the compounds towards M. smegmatis makes them potential leads in the search for new narrow spectrum antibiotics against M. tuberculosis.
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