Pa. Radel et Sb. Kahl, ENANTIOSELECTIVE SYNTHESIS OF L-CARBORANYLALANINE AND D-CARBORANYLALANINE, Journal of organic chemistry, 61(14), 1996, pp. 4582-4588
The enantioselective synthesis of L- and D-carboranylalanine is report
ed. Imides 13 and 14 are treated with titanium tetrachloride, DIEA, an
d NBS to introduce a bromo functionality in 98:2 ratio at the alpha-ce
nter. Azide displacement with TMGA, displacement of the oxazolidinone
template with titanium tetrabenzyloxide, and subsequent hydrogenolysis
permits L- or D-carboranylalanine to be isolated in high stereoselect
ivity and 35-40% yields overall.