Palladium-catalyzed defluorinative alkynylation of polyfluoroalkyl ketones with alkynes for the synthesis of fluorinated fused furans

Abstract

A Pd-catalyzed C-F bond alkynylation of polyfluoroalkyl ketones with terminal alkynes has been developed. The method gives access to a range of modular perfluoroalkyl- and alkynyl-substituted furan derivatives in moderate...

Three-Component Bisannulation for the Synthesis of Trifluoromethylated Tetracyclic Aza-Aromatics through Six C(sp3)–F Bond Cleavage and Four C–N Bond Formation

“…On the basis of these obtained results, a proposed mechanism is outlined in Scheme . − Initially, a successive defluorination of perfluoroalkyl substrate 1 under the effect of the alkali-metal base gives unstable naphthalen-1­(4 H )-one intermediate B , which further undergoes the condensation with benzamidine 2 to afford the imine species C . The following intramolecular defluorinative amination of resultant intermediate C through 7- endo-trig cyclization furnishes the ring-closure product E .…”

“…Selective trifluoromethylation of a specified C–H bond in (hetero)­arenes remains a fundamental challenge. Recently, our laboratory has leveraged the distinctive fluorine effect for heteroannulation, where the synthetic linchpin for realizing the assembly of fluoro-organic molecules is controlled by successive selective defluorination at different centers. − Reactive quinoid species are key intermediates for the C–F bond functionalization and heterocycle construction. Although the reactions of perfluoroalkyl ketones with amidines to form pyrimidine derivatives have been well studied, the accurate six C­(sp 3 )–F bond cleavage at three different sites by using these quinoid species has never been reported until now .…”

Multiple-fold C–F bond functionalization for the synthesis of (hetero)cyclic compounds: fluorine as a detachable chemical handle

“…A palladium-catalyzed alkynylation of PFKs through a sequence of C–C(sp) bond forging, successive defluorination, and ring-closure relay, accompanied by the simultaneous cleavage of four C(sp 3 )–F bonds and the formation of new C–C/C–O bonds allowed the regio-specific assembly of modular internal alkynes (Scheme 73). 122 In this variant, in addition to simple terminal alkynes, functionalized alkyne derived from estrone, conjugated 1,3-diyne, and enyne were smoothly converted into the corresponding products 73-4–73-6 in 34–46% yields. Preliminary mechanistic studies revealed that the reaction presumably proceeds through a carbonyl-assisted oxidative addition of palladium to the C(sp 2 )–F bond of a α,β-unsaturated carbonyl compound 73-7 , which is formed from PFK after eliminating a molecule of HF.…”