Stereoselective cobalt-catalyzed halofluoroalkylation of alkynes

Abstract

Stereoselective additions of functionalized reagents to unsaturated hydrocarbons are attractive due to the high atom economy, modularity and rapid generation of complexity. We report a stereoselective cobalt-catalyzed (E)-halofluoroalkylation of alkynes/alkenes that under mild conditions (2 mol% cat., 20 °C, acetone/water, 3 h). This reaction operates via a radical chain mechanism involving terminal halogen atom transfer which obviates the need for a stoichiometric sacrificial reductant.

Intermolecular Iodofluoroalkylation of Unactivated Alkynes and Alkenes Mediated by Manganese Catalysts

“…The ATRA reaction is E selective, with an E/Z ratio larger than 90:10. A wide range of phenylacetylene derivatives containing electron-donating and electron-withdrawing substituents, such as methyl (4,13,15), methoxyl (5,17), fluoro (6), chloro (7,14), bromo (8,16), trifluoromethoxy (9), ester (10), phenyl (11), and aldehyde (12), worked well, thus affording (10) EtOAc 74 4 Mn 2 (CO) 10 (10) MeOH 69 5 Mn 2 (CO) 10 (10) decalin 77 6 Mn 2 (CO) 10 (10) cyclohexane 85 7 Mn(CO) 5 Br (10) cyclohexane 60 8 Fe 2 Cp 2 (CO) 4 (10) cyclohexane 43 9 Mn(OAc) 3 (10) cyclohexane 0 10 Mn(acac) 3 (10) cyclohexane 0 11…”

“…Co 2 (CO) 8 (10) cyclohexane 0 12 Re 2 (CO) 10 (10) cyclohexane 0 13 Mn 2 (CO) 10 (5) cyclohexane 80 14 [c] Mn 2 (CO) 10 (10) cyclohexane 85 15 none cyclohexane 0 16 [d] Mn 2 (CO) 10 (10) cyclohexane 0…”

A Carbene‐Extended ATRA Reaction

“…Following our recent report of a cobalt‐catalyzed ATRA reaction of alkynes and alkyl halides, we commenced our investigations into a C 1 ‐extended ATRA process with the reaction between phenylacetylene ( 1 a ), n ‐perfluorobutyl iodide ( 2 a ), and the commercially available carbene precursor trimethylsilyldiazo‐methane ( 3 a ). Under very similar conditions as reported for the cobalt‐catalyzed ATRA reaction (Scheme a), the three‐component reaction was performed with catalytic CoBr 2 and dppbz (1,2‐bis(diphenylphosphino)benzene) in the presence of zinc as co‐catalyst. To our delight, the ATRA adduct 4 a was obtained in 27 % yield while the C 1 ‐elongated alkene 5 a was the major product with 51 % yield ( Z / E =4:1, Scheme b).…”

“…I) and the increased steric bulkiness in the corresponding transition state (cf. the high E selectivity in ATRA with t ‐BuI and our earlier studies). With less electrophilic non‐fluorinated alkyl halides, ATRA between the alkyl halide and TMSCHN 2 exclusively took place while the subsequent alkyne insertion did not proceed.…”

Visible-light Promoted Atom Transfer Radical Addition−Elimination (ATRE) Reaction for the Synthesis of Fluoroalkylated Alkenes Using DMA as Electron-donor

“…Alkenes play a ubiquitous role in the realm of chemical synthesis due to their enriched reactivity and abundance, fluoroalkylation of carbon-carbon double bonds is an attractive method for accessing fluorine containing compounds. Since 1945, atom transfer radical addition (ATRA) has extensively been utilized for fluoroalkylation of alkenes [20][21][22][23][24][25][26][27][28][29]. However, the preparation of alkenes containing fluorinated functional groups via Heck-type reaction were less studied owning to the lack of efficient and general strategies [30][31][32].…”