Abstract
A new multistage synthesis of the N-borylated dipeptide B12-PheGlyOH has been proposed. The approach is based on the reaction of nucleophilic addition of amino acid derivatives to the [B12H11NCCH3]– anion. The products of each stage have been characterized by multinuclear NMR spectroscopy, IR absorption spectroscopy, and ESI mass spectrometry.
Highlights
Neutron capture therapy (NCT) is a binary method of non-invasive treatment of malignant tumors [1]; the development of this method is directly related with the search for new effective therapeutic agents [2]
It was previously shown that the addition of nucleophilic reagents of various natures to nitrile functional groups in anionic boron clusters can be considered as a convenient way of directed synthesis of their substituted derivatives [12,13,14,15,16,17,18,19,20,21,22,23,24], including those based on biologically active substances [6, 25] and biomimetic systems [26, 27]
It was found that the addition of tertbutyl esters of proteinogenic amino acids to nitrile derivatives of the closo-decaborate anion and their subsequent selective hydrolysis is a convenient method for the preparation of N-borylated peptides [28]. tert-Butyl esters of amino acids are used due to the stability of amidine-closo-borates under the conditions of their hydrolysis [29]
Summary
Neutron capture therapy (NCT) is a binary method of non-invasive treatment of malignant tumors [1]; the development of this method is directly related with the search for new effective therapeutic agents [2]. An important requirement for compounds used for 10B-NCT is a high selectivity of accumulation in tumor tissues and a high content of boron in molecules to create the required therapeutic concentration [3]. Closo-Dodecaborate anion [B12H12]2– attracts close attention of researchers when creating new agents for 10B-NCT due to its low toxicity and high boron content [4,5,6]. The effectiveness of drugs for 10B-NCT depends on the selectivity of the accumulation of boron compounds in tumor cells, which requires the introduction of vector groups into the cluster cage. It was found that the addition of tertbutyl esters of proteinogenic amino acids to nitrile derivatives of the closo-decaborate anion and their subsequent selective hydrolysis is a convenient method for the preparation of N-borylated peptides [28]. It was found that the addition of tertbutyl esters of proteinogenic amino acids to nitrile derivatives of the closo-decaborate anion and their subsequent selective hydrolysis is a convenient method for the preparation of N-borylated peptides [28]. tert-Butyl esters of amino acids are used due to the stability of amidine-closo-borates under the conditions of their hydrolysis [29]
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