Nickel borohydride
Recent Literature
Benzyl esters of various acids can be chemoselectively cleaved on treatment with
nickel boride in methanol at ambient temperature to give the parent carboxylic
acids in high yields. Esters such as methyl, ethyl, tert-butyl, and
trityl esters as well as benzyl ethers, tert-butyl ethers, and N-benzylamides
remain unaffected under these conditions.
J. M. Khurana, R. Arora, Synthesis, 2009,
1127-1130.
A nickel boride catalyst prepared in situ from NiCl2 and sodium
borohydride allowed facile reductions of a wide range of nitroarenes, aliphatic
nitro compounds, and organic azides. Addition of modified nanocellulose enabled
lower catalyst loading in nitro reductions. The protocols are compatible with a
one-pot Boc-protection to provide the corresponding carbamates.
G. Proietti, K. J. Prathap, X. Yu, R. T. Olsson, P. Dinér, Synthesis, 2022, 54,
133-146.
A nickel boride catalyzed reduction of nitriles allows the preparation of Boc protected
amines. The catalytic
use of nickel(II) chloride in combination with excess sodium borohydride is
environmental benign and tolerates air and moisture. Although the yield is
sometimes moderate, the cleanliness of the method is exceptional.
S. Caddick, D. B. Judd, A. K. de K. Lewis, M. T. Reich, M. R. V. Williams, Tetrahedron, 2003, 59, 5417-5423.