Potassium Fluoride-Celite1

KF/Celite
(KF)

[7789-23-3]  · FK  · Potassium Fluoride-Celite  · (MW 58.10) (Celite)

[61790-53-2]

(mild heterogeneous basic catalyst for alkylation1 and Michael addition5)

Form Supplied in: white solid.

Preparative Method: Celite 545 (20.0 g) is mixed with Potassium Fluoride (20.0 g) in water (500 mL), and the water removed at 50-60 °C in a rotary evaporator. The solid obtained is then shaken in MeCN (100 mL), filtered, washed with two portions (50 mL) of MeCN and dried in a desiccator at rt.

General Discussion.

The main use of KF/Celite is as a catalyst for alkylation with alkyl halides. The alkylation proceeds smoothly with aniline, amines, and thiophenol in MeCN between rt and 70 °C, dependent on reactivity of the alkyl halides.1 Workup can be carried out under nonaqueous conditions: addition of ether, filtration, washing with ether, evaporation of the solvents, and distillation or recrystallization.1 Alkylation of 1,3-diketones gives monoalkylated products.1 1,3-Indanedione gives rise to dialkylated 1,3-indanedione exclusively, even if less than 2 equiv of alkylating reagent are used (eq 1).2

A nucleophilic aromatic substitution on activated nitro- or chlorobenzenes is effected by KF/Celite. Reaction of various 1,3-diketones with cyclopentadienyliron-complexed nitro- or chlorobenzenes gives the corresponding 1,3-diketone substituted products without deacetylated byproducts (eq 2).3 In contrast, deacetylated byproducts are often observed using alternative methods unless precautions are taken during workup.4

KF/Celite-catalyzed intramolecular Michael addition provides a new approach to flavanones. One example is the synthesis of bavachinin by intramolecular addition of a phenol group to an a,b-unsaturated ketone in methanol (eq 3).5 Use of free KF, KF/alumina, and Tetra-n-butylammonium Fluoride in this reaction is less successful.5

Related Reagents.

Lithium Fluoride; Potassium Fluoride; Potassium Fluoride-Alumina.


1. Ando, T.; Yamawaki, J. CL 1979, 45.
2. Bloch, R.; Orvane, P. SC 1981, 11, 913.
3. Sutherland, R. G.; Abd-El-Aziz, A. S.; Piorko, A.; Lee, C. C. SC 1987, 17, 393.
4. Moriarty, R. M.; Gill, U. S. OM 1986, 5, 253.
5. Harwood, L. M.; Loftus, G. C.; Oxford, A.; Thomson, C. SC 1990, 20, 649.

Qi Han & Hui-Yin Li

Du Pont Merck, Wilmington, DE, USA



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