ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
2021, VOL. 53, NO. 4, 369–378
EXPERIMENTAL PAPER
Solvent-free, Efficient Transamidation of Carboxamides
with Amines Catalyzed by Recyclable Sulfated
Polyborate Catalyst
Anil S. Mali , Krishna Indalkar , and Ganesh U. Chaturbhuj
Institute of Chemical Technology, Matunga, Mumbai, India
ARTICLE HISTORY Received 4 September 2020; Accepted 22 October 2020
Transamidation is a significant reaction in organic and medicinal chemistry. The amide is
one of the most important functional groups used in organic transformations, and it is
found in a wide variety of dyes, polymers, peptide dendrimers, agrochemicals, pharma-
ceuticals, and biologically active compounds.1–5 In 2007, the American Chemical Society
Green Chemistry Institute Pharmaceutical Roundtable (ACS GCIPR) designated amida-
tion as a challenging goal in organic chemistry for which green, efficient, and sustainable
alternative methods are required.6 The amide link forms the backbone of proteins and
peptides.7 It is an inherent part of many natural products such as capsaicin, piperine, N-
acetyl anthranilic acid, taxol, and penicillin-G and drugs such as mepivacaine, lidocaine,
articaine, amoxicillin, acetazolamide, valsartan, atorvastatin, protirelin, captopril, enalapril,
chloramphenicol, methyprylon, benzipram, zolpidem, and many others. Fatty acid amides
exhibit excellent antimicrobial, anti-inflammatory, antiproliferative, and antitubercular
activities.5 Amides are useful intermediates for the synthesis of pharmacologically import-
ant heterocycles containing nitrogen and oxygen.9 It has been estimated that nearly 25%
of active pharmaceutical ingredients contain amide functional groups.3
Transamidation involves the cleavage of the C-N bond in an amide reactant and the
formation of a new C-N bond in the product.10 The exchange of the amine moiety of
an amide is a conceptually simple but rare organic transformation, due to the modest
reactivity of amides. Traditionally, amide synthesis involves the reaction of amines with
carboxylic acid derivatives (chlorides, anhydrides, or esters), aldehydes, alcohols, or
hydration of nitriles and hydroamination of alkynes.11,12 These procedures are often
limited by harsh reagents, high temperature, tedious isolation, or the generation of
waste. In this vein, a number of traditional name reactions, including the Schmidt,13
Ritter,14 Beckmann,15 and Ugi16 reactions have been reported for amide synthesis.
Up to the present, the literature for transamidation includes the use of Bronsted acid
ionic liquid,17 KOtBu,18,19 polymer-bound HfCl4,20 AlCl3,21 Eu(OTf)3,22 ZrCl4,23
Ti(NMe2)4,24 Sc(OTf)3,25 CeO2,26 binuclear Mn(II) complexes,27 Cp2ZrCl2,28 Fe(III),11
Rh(II) NHC complexes,29 benzoic acid,30 boric acid,31 L-proline,12 hypervalent iodine,32
copper acetate,33 MnO2,34 H2SO4-SiO2,35 H-b Zeolite,9 Chitosan,36 B(OCH2CF3)3,37
CONTACT Ganesh U. Chaturbhuj
Institute of Chemical Technology, Matunga, Mumbai
400019, India
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