Copper(II) acetylacetonate: An inexpensive multifunctional catalyst

Abstract

(A) Benzylation of Alcohols: Sirkecioglu and co-workers have found that selective O-benzylation of primary hydroxy compounds can be performed in the presence of catalytic amounts of Cu(acac) 2 and benzyl chloride in good to high yields. (B) X-H Insertion Reactions: Cu(acac) 2 can catalyze many X-H (X = N, O, S, P, Se) insertion reactions. This scheme illustrates a recent example of an intramolecular N-H insertion reaction from diazoketones for the construction of fully substituted azetidines by Correia and Burtoloso.7 (C) Reduction of Aromatic Nitro Compounds: Hanaya and co-workers reported a protocol for the reduction of aromatic nitro compounds to amines in high yields and in short reaction times in the presence of NaBH 4 and Cu(acac) 2 as catalyst. (D) Cyclopropanation: Cu(acac) 2 catalyzes both intermolecular and intramolecular cyclopropanation of double bonds with diazo compounds. (E) Aziridination of Olefins: Kantam and co-workers have reported a novel recyclable catalytic system for aziridination of olefins using PhI=NTs in the presence of Cu(acac) 2 immobilized in ionic liquids. This methodology furnishes aziridines in good yields and with fast reaction rates. (F) Reduction of α-Diazo Carbonyl Compounds: Diazo carbonyl compounds are reduced in the presence of Cu(acac) 2 and Bu 3SnH. (G) Synthesis of Conjugated Enynes from Alkenyldialkylboranes: The cross-coupling reaction of (E)- and (Z)-1-alkenyldialkylboranes with (trimethylsilyl)ethynyl bromide in the presence of Cu(acac) 2 furnishes conjugated enynes under very mild conditions. © Georg Thieme Verlag Stuttgart.