Iron-Catalyzed Reductive Ring Opening/gem-Difluoroallylation of Cyclopropyl Ketones

Abstract

By merging C−C and C−F bond cleavage, we developed a regioselective ring opening/gem-difluoroallylation of cyclopropyl ketones with α-trifluoromethylstyrenes, which proceeds under the catalysis of iron with the combination of manganese and TMSCl as the reducing agents, providing a new entry to the synthesis of carbonyl-containing gem-difluoroalkenes. Remarkably, the ketyl radical-induced selective C−C bond cleavage and the following generation of more-stable carbon-centered radicals enable complete regiocontrol of this ring opening reaction for various substitution patterns of the cyclopropane ring.

Chromium-catalyzed allylic defluorinative acylation of trifluoromethyl-substituted alkenes with acyl oxime esters

“…2 Consequently, the synthesis of gem -difluoroalkenes has received considerable attention from organic chemists in the last decades, 3 leading to the establishment of two main strategies, which rely on functional group conversion 4 or allylic defluorinative cross-coupling of trifluoromethyl-substituted alkenes. 5 In the recent years, our group 6–12 and others 13 implemented the reductive coupling in the allylic defluorination of trifluoromethyl-substituted alkenes, enabling the efficient synthesis of structurally complex functional-group-rich gem -difluoroalkenes starting from readily available organic electrophiles, which include alkyl halides, 6,13 c , d carbonyl compounds, 7,13 e acetals, 8 epoxides, 9 cyclic oxime esters, 10,13 a activated carboxylic acid esters, 13 b Katritzky salts, 11 cycloalkyl silyl peroxides, 12 and alkene-tethered aryl halides 13 f (Scheme 1A).…”

Nickel-Catalyzed Cross-Electrophile Ring Opening/gem-Difluoroallylation of Aziridines

“…gem -Difluoroalkenes have attracted increased interest from the organic community in recent years , because such moieties are not only present as characteristic structural units in numerous biologically active compounds but also serve as the precursors to reach other fluorine-containing compounds . Among many strategies, transition-metal-catalyzed allylic defluorinative cross-electrophile coupling (XEC) of trifluoromethyl-substituted alkenes developed by Wang − and others offers a unique reaction pathway to prepare functional-group-rich gem -difluoroalkenes starting from readily available organic electrophiles, including alkyl halides, ,, carbonyl compounds, , acetals, epoxides, oxime esters, , activated carboxylic esters, Katritzky salts, cycloalkyl silyl peroxides, and alkene-tethered aryl halides…”