Copper(I) Acetylacetonate

[14220-26-9]  · C5H7CuO2  · Copper(I) Acetylacetonate  · (MW 162.65)

(catalyst for the decomposition of diazo compounds2 and for Michael addition3,4)

Alternate Names: cuprous acetylacetonate; (2,4-pentanedionato)copper.

Physical Data: prepared in situ.1

Solubility: sol dioxane, MeNO2, MeCN, acetic acid.3

Preparative Method: can be prepared by reacting acetylacetone (2,4-Pentanedione) with an ammoniacal solution of CuOH (copper(I) hydroxide).1

Handling, Storage, and Precautions: air-sensitive; irritant.

Catalysis of the Decomposition of Diazo Compounds.

Copper(I) acetylacetonate is an effective catalyst for the decomposition of a-diazo ketones to copper carbenoids, which can undergo carbene insertion reactions (eq 1). This strategy was used in a synthesis of cis-jasmone (eqs 2 and 3).2 However, the catalyst more commonly used in the decomposition of diazo compounds is Copper(II) Acetylacetonate, which is commercially available.2

Hou reported an intramolecular carbene insertion reaction catalyzed by this reagent and also by Palladium(II) Acetate.5 The reaction of a-O-allyl- or a-N-allyl-a-diazopropanone derivatives, such as CH2=CHCH2OCH(Ph)COCHN2, give high yields of the corresponding pyranones in CH2Cl2 at room temperature under the catalysis of copper(I) acetylacetonate.5

Catalysis of Michael Additions.3

Cu(acac) catalyzes the Michael addition of b-dicarbonyls to 2-cyclohexenones and 2-cyclopentenones in the presence of Boron Trifluoride Etherate (eqs 4-6).3,4

It is believed that the catalyzed Michael addition has the mechanism shown in eq 7. Because the metal chelate is very stable, this catalytic method is irreversible, which explains the high yield of the method compared to the base-catalyzed Michael addition.3,4

Under a variety of conditions with this catalyst, the substituted a,b-unsaturated ketones and esters (3-6) are inert to Michael addition.

Related Reagents.

Bis(acetylacetonato)zinc(II); Copper(II) Acetylacetonate; Tris(acetylacetonato)indium; Manganese(III) Acetylacetonate; Nickel(II) Acetylacetonate; Palladium(II) Acetylacetonate; 2,4-Pentanedione; Tris(acetylacetonato)iron(III); Vanadyl Bis(acetylacetonate).

1. Emmert, B.; Gsottschneider, W.; Stanger, H. CB 1936, 69, 1319.
2. McMurry, J. E.; Glass, T. E. TL 1971, 2575.
3. Ko&cbreve;ovský, P.; Dvo&rbreve;ák, D. CCC 1988, 53, 2667.
4. Ko&cbreve;ovský, P.; Dvo&rbreve;ák, D. TL 1986, 27, 5015.
5. Hou, Y.-S.; Chang, R.-C. H 1991, 32, 1089.

Edward J. Parish & Shengrong Li

Auburn University, AL, USA

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