Cu(0)/Selectfluor System-Mediated Mild Synthesis of Fluorinated Fluorenones from Nonaromatic Precursors (1,6-Enynes) Involving C–C Single Bond Cleavage

Abstract

A novel and facile method for the mild construction of fluorinated fluorenones from nonaromatic precursors (1,6-enynes) mediated by a Cu(0)/Selectfluor system has been successfully achieved. Preliminary mechanistic investigations indicate that the reaction may proceed via an unprecedented annulation/C-C single bond cleavage/fluorination sequence.

Unexpected Metal-Free Fluorination and Oxidation at the C-4 Position of Pyrazoles Promoted by Selectfluor

“…19,30 This type of fluorination has already been described in the literature; however, this paper reports for the first time an efficient metal-free methodology for the direct insertion of a fluorine atom, elimination of the substituents of the C-4 position, and the subsequent restoration of the pyrazole aromaticity. Moreover, under the same standard conditions it was also possible to obtain oxidation products from compounds with groups that have longer alkyl chains attached to the C-4 position of the pyrazole ring.…”

Facile and Diverse Synthesis of Benzo[b]fluorenone Derivatives through a Copper/Selectfluor‐Catalyzed Tandem Annulation of 1,6‐Enynes

“…Studies on the Intramolecular Kinetic Isotope Effects (KIE) Based on Substrate [D]1a: Compound [D] 1a was synthesized from 1‐[2‐(3,3‐dimethylbut‐1‐yn‐1‐yl)phenyl]ethanone and o ‐deuterated 4‐methyl benzaldehyde (deuterium enrichment ≥99 %) according to the reported procedure for the synthesis of 1 , …”

“…As part of our research into the construction of carbocycles from 1, n ‐enynes, we recently developed a Cu 0 /Selectfluor‐catalyzed oxidative cyclization of 1,5‐enynes to give 3‐formyl‐1‐indenone derivatives; this reaction proceeds by a tandem annulation/C–C‐bond‐cleavage process (Scheme c) . Our further application of the Cu 0 /Selectfluor system in the annulation of 1,6‐enynes led to a facile synthesis of a diverse array of benzo[ b ]fluorenones under mild reaction conditions (Scheme d) . In this paper, we describe these findings.…”

A Perspective on Synthesis and Applications of Fluorenones

“…2.0 equiv. benzonitrile (87) treated with iodobenzene (77) in the presence of 10 mol % of Pd(MeCN) 2 , 1.1 equiv. Ag 2 O, 1.0 equiv.…”

“…Selectfluor in polar aprotic solvent (acetonitrile) at 45°C for 1.5 h led to fluorenones in 92 % yield (Scheme 64). [77] High temperature (80°C ) with inorganic bases (K 2 CO 3 , NaHCO 3 ) lowered the yields but low temperature (45°C ) with K 2 CO 3 led up to 90 % yields of fluorenones (Scheme 64). At R 1 position electron-donating groups and aryl ring gave desired products in up to 56 to 80 % yields, whereas electron-withdrawing groups (Cl, F, and CF 3 ) led to annulated products.…”