Preparation of enantiomerically pure derivatives of (3-amino-1,2-dicarba-closo-dodecaboran-1-yl)acetic acid

(7,8-Dicarba-nido-undecaboran-7-yl)acetic acid: synthesis of individual enantiomers and the first example of the determination of the absolute configuration of chiral monosubstituted nido-carborane

“…Recently, the possibility of obtaining enantiomerically enriched Fig. 1 Planar-chiral derivatives of closo-and nido-carboranes studied earlier [7][8][9] and in this work.…”

“…To assign the stereo configuration of the resulting nido-carborane derivatives, we independently synthesized potassium (nido-carboran-7-yl)acetate ((S P )-1-K) from benzyl (R P )-3-amino-(closo-carboran-1-yl)acetate ((R P )-9) obtained as described earlier. 8 Scheme 1 General strategy for the preparation of individual enantiomers of (nido-carboran-7-yl)acetic acid.…”

“…s), 45.5 (br. s), 45.4, 38.6, 36.4, 29.9, 19.3, 18. (S)-1-(tert-Butoxycarbonyl)amino-2-{2-[1,2-dicarba-closo-dodecaboran-1-yl)acetylamino]-4-methylpentanoylamino}-benzene (8).…”

“…Colourless powder, mp 218-220 1C (decomp.). 8,165.8,152.9,131.7,128.7,125.7,125.3,123.8,123.3,79.4,71.3,61.1,52.0,41.8,40.4,28.0 (3C),24.2,22.7,21.7. Anal.…”

“…Previously, we have proposed methods for the preparation of enantiomerically pure derivatives of closo -carboranyl amines A 7 and amino acids B , 8 as well as nido -carboranyl derivatives of amino acids C 9 (Fig. 1) and assigned their stereo configuration.…”