Download PDF
Synlett 2006(2): 327-328  
DOI: 10.1055/s-2006-926228
SPOTLIGHT
© Georg Thieme Verlag Stuttgart · New York

Cu(BF4)2 ·xH2O: A Versatile Catalyst

Raj Kumar Khunger*
Department of Medicinal Chemistry, National Institute of ­Pharmaceutical Education and Research (NIPER), SAS Nagar, Punjab 160062, India
e-Mail: khunger_raj@rediffmail.com;
Further Information

Publication History

Publication Date:
24 January 2006 (online)

   Permissions and Reprints All articles of this category

Introduction

Copper(II) tetrafluoroborate hydrate Cu(BF4)2·xH2O [CAS: 314040-98-7] is a corrosive, moisture-sensitive, blue crystalline solid readily soluble in water and sparingly soluble in alcohols. Cu(BF4)2·xH2O is readily available and widely used as the starting material for homometallic, trinuclear heteroscorpionate [1] complexes applied in the studies of electronic and magnetic properties. It causes decomposition of 9-diazofluorene in acetonitrile solvent. [2] As it does not require special storage conditions and is safe and stable under normal environmental conditions, Cu(BF4)2·xH2O has emerged as one of most useful reagent in various transformations such as acylation reactions and 1,1-diacetate formations. In all the cases, this reagent has been found to be superior to other available Lewis acids such as triflates, tetrafluoroborates and perchlorates with regard to short reaction times, requirement of stoichio­metric amount of reagent, mild reactions conditions, solvent-free conditions and low cost. Further, the distinct advantage of the use of Cu(BF4)2.xH2O as a catalyst for thia-Michael addition reactions [3] with α,β-unsaturated ­carbonyl compounds is evidenced by the fact that the ­reaction of 3-methylcyclohexenone with thiophenol ­afforded the product in 45 minutes while the corresponding reaction did not proceed in the presence of an ionic ­liquid. [4]