Synthesis of optically active dodecaborate-containing l-amino acids for BNCT

Authors:   Shintaro Kusaka,Yoshihide Hattori,Kouki Uehara,Tomoyuki Asano,Shinji Tanimori,Mitsunori Kirihata,
Journal: Applied Radiation and Isotopes
https://doi.org/10.1016/j.apradiso.2011.03.042
Abstract: A convenient and simple synthetic method of dodecaboratethio-l-amino acid, a new class of tumor-seeking boron carrier for BNCT, was accomplished from S-cyanoethylthioundecahydro-closo-dodecaborate (S-cyanoethyl-10BSH, [10B12H11]2−SCH2CH2CN) and bromo-l-α-amino acids by nearly one step S-alkylation. An improved synthesis of S-cyanoethyl-10BSH, a key starting compound for S-alkylation, was also performed by Michael addition of 10BSH with acryronitrile in high yield. Four kinds of new dodecaboratethio-l-amino acids were obtained in optically pure form without the need for any optical resolution.