J. Shaw, D. H. Grayson, I. Rozas
2015
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1
Influential Citations
8
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Abstract
Guanidine is one of the most versatile functional groups in chemistry; compounds containing this system have found application in a diversity of biological activities, and in this chapter, the advances in the field of the synthesis of guanidines are presented. First, the preparation of acyclic guanidines involving the reaction of an amine with an activated guanidine precursor followed by the deprotection to yield the corresponding free guanidine is discussed. Thiourea derivatives as guanidylating agents have been widely used as guanidine precursors using coupling reagents or metal-catalysed guanidylation. Alternatively, S-methylisothiourea has shown to be a very efficient guanidylating agent, and N,N′,N″-trisubstituted guanidines have also been used to install the guanidine functionality. Despite the similarity between urea and thiourea, the former has received much less attention; however, its application in guanidine synthesis has also been proved. Examples of the preparation of guanidines using cyanamides that react with derivatised amines as well as the use of copper-catalysed cross-coupling chemistry are also presented. Moreover, cyclic guanidines such as 2-aminoimidazolines (five-membered rings), 2-amino-1,4,5,6-tetrahydropyrimidines (six-membered rings) and 2-amino-4,5,6,7-tetrahydro-1H-1,3-diazepines (seven-membered rings) are present in many natural products and compounds of medicinal interest. Accordingly, an overview of the methods found in the literature for the preparation of these cyclic guanidines is presented. Finally, some biological applications of guanidines as DNA minor groove binders, kinase inhibitors and α2-noradrenaline receptors antagonists are discussed.