1,3-Dimethylimidazol-2-ylidene borane (diMe-Imd-BH3)
NHC-trihydroboranes are white solids that are stable to air, water, and even chromatography. However, 1,3-dimethylimidazol-2-ylidene borane is a suprisingly good hydride donor that is comparable to anionic reagents such as NaCNBH3. The reagent can be used for reductive amination procedures and even for reduction of carbonyl compounds if silica gel is present. Besides, NHC-boranes are attractive reagents for radical, pericyclic and organometallic reactions.
Recent Literature
NHC-boranes such as 1,3-dimethylimidazol-2-ylidine trihydridoborane serve as
practical hydride donors for the reduction of aldehydes and ketones in the
presence of silica gel to give alcohols in good yields under ambient conditions.
Aldehydes are selectively reduced in the presence of ketones. The process is
attractive because all the components are stable and easy to handle and because
the isolation procedure is convenient.
T. Taniguchi, D. P. Curran, Org. Lett., 2012,
14, 4540-4543.
N-heterocyclic carbene boranes (NHC-boranes) are among the most nucleophilic
classes of neutral hydride donors. Reductions of highly electron-poor C=N and
C=C bonds provide hydrogenation products along with new, stable borylated
products. The results suggest that NHC-boranes have considerable untapped
potential as neutral organic reductants.
M. Horn, H. Mayr, E. Lacôte, E. Merling, J. Deaner, S. Well, T. McFadden, D. P. Curran, Org. Lett., 2012,
14, 82-85.
The use of 1,3-dimethylimidazol-2-ylidene borane (diMeImd-BH3)
enables a decyanation of secondary aliphatic nitriles and a 2-fold decyanation
of malononitriles leading to alkanes.
T. Kawamoto, K. Oritani, A. Kawabata, T. Morioka, H. Matsubara, A. Kamimura, J. Org. Chem., 2020, 85,
6137-6142.
