Copper(II) Sulfate

Biographical Sketches

Guilherme Rocha Pereira was born in 1977 at Belo Horizonte, ­Minas Gerais, Brazil. He obtained his B.Pharm. in 2001 from the Universidade Federal de Minas Gerais, Brazil. In 2002, he moved to the United States of America to work at a drug discovery company for four years. In 2006, he joined the Kobayashi’s research group at the University of California San Diego, UCSD, where he received his M.Sc. in Organic Chemistry. He moved back to Brazil in 2007, were he is currently working for his Ph.D. under the supervision of Dr. Rossimiriam Pereira de Freitas at the Universidade Federal de Minas Gerais. His research interest is focused on the modification of [60]fullerene via Bingel-type reaction and copper-catalyzed azide-alkyne cycloaddition (CuAAC).

Introduction

Copper(II) sulfate (CuSO₄) exists as a series of compounds that differ in their degree of hydration. The anhydrous form is a gray-white powder, whereas the pentahydrate, the most commonly encountered salt and commercially available, is bright blue. The hydrated copper sulfate occurs in nature as chalcanthite [¹] (pentahydrate), and two more rare ones: bonattite (trihydrate) [²] and boothite (heptahydrate). [³] It can be made by the action of sulfuric acid on a variety of copper(II) compounds, for example the basic copper(II) oxide or by electrolyzing sulfuric acid using copper electrodes. The anhydrous salt, prepared by previous heating of the pentahydrate salt, is used in transacetalization reactions as a dehydrating component. [4] Copper(II) sulfate pentahydrate is used in many organic transformations under mild and convenient conditions to afford the products in high yields. In addition, copper(II) sulfate pentahydrate is a source to prepare copper complexes. [5] [6]

Abstracts

(A) Preparation of 1,4-Disubstituted 1,2,3-Triazoles: The copper-catalyzed azide-alkyne cycloaddition (CuAAC) broadly know as ‘click reaction’ has found a widespread use. [7] The reaction is carried out in a mixture of organic and aqueous systems employing copper(II) sulfate pentahydrate and a reducing agent. The triazole formed is essentially chemically inert to reactive conditions, such as oxidation, reduction and hydrolysis.
(B) Preparation of 3,5-Disubstituted Isoxazoles: The copper(I)-catalyzed cycloaddition between nitrile oxides and terminal acetylenes gives 3,5-disubstituted isoxazoles. [8] This ‘click’ reaction is a convenient one-pot, three-step procedure using stoi­chiometric amounts of the reagents minimizing the formation of by-products.
(C) N-Arylation of Imidazoles: A simple, highly efficient, economical, and environmentally friendly protocol for copper-catalyzed N-arylation of imidazoles in water has recently being reported. [9] The catalytic system can be easily generated using a mixture of CuSO4˙5H2O and bidentate N,N-ligands to promote the N-arylation of imidazoles with aryl halides with up to 95% yield.
(D) Formation of Ynamides: A general and efficient method for the coupling of a wide range ­of amides with alkynyl bromides also involves a catalytic protocol using CuSO4˙5H2O and a ligand to produce a diverse array of ­ynamides. [¹0] The catalyst system directs the sp C-N bond formation leading to the desired product.
(E) Epoxidation: Epoxidation of trisubstituted steroid olefins by a nonconcerted pathway was promoted by a mixture CuSO4 and KMnO4 in t-BuOH and CH2Cl2 at reflux (Parish reagent). [¹¹] During epoxidations with the Parish oxidizing mixture there is considerable evolution of oxygen; however, without copper (II), little oxygen is evolved and little or no epoxide is formed.
(F) Deprotection of Acetals, Etherifications, and Iodolactonizations: Deprotection of acetals, catalyzed by a convenient system of CuSO4 and NaI has been developed. [¹²] The oxidation of NaI using CuSO4 in acetone generates I2 in situ that allows chemoselective deprotection of acetals. Other applications include etherifications and iodolactonizations.

References

• 1 Schofield PF. Knight KS. Physica B  2000,  276-278:  897 
• 2 Bastidas JM. López-Delgado A. López FA. Alonso MP. J. Mater. Sci.  1997,  32:  129 
• 3 Piilonen PC. Ercit TS. Roberts AC. Am. Mineral.  2005,  90:  768 
• 4 Morgenlie S. Acta Chem. Scand.  1973,  27:  3609 
• 5 Graddon DPL. J. Inorg. Nucl. Chem.  1960,  14:  161 
• 6 Imuta M. Ziffer H. J. Am. Chem. Soc.  1979,  101:  3990 
• 7 Meldal M. Tornøe CW. Chem. Rev.  2008,  108:  2952 
• 8 Hansen TV. Wu P. Fokin VV. J. Org. Chem.  2005,  70:  7761 
• 9 Liang L. Li Z. Zhou X. Org. Lett.  2009,  11:  3294 
• 10 Zhang X. Zhang Y. Huang J. Hsung RP. Kurtz KCM. Oppenheimer J. Petersen ME. Sagamonova IK. Shen L. Tracey MR. J. Org. Chem.  2006,  71:  4170 
• 11 Baqi Y. Giroux S. Corey EJ. Org. Lett.  2009,  11:  959 
• 12 Bailey AD. Cherney SM. Anzalone PW. Anderson ED. Ernat JJ. Mohan RS. Synlett  2006,  215