Atmospheric-pressure, bench-scale catalytic hydrogenations are a routine protocol for a variety of functional group interconversions. However, in addition to cost considerations, the use of compressed H2(g) presents potential handling hazards. To ameliorate this, on-demand generation of H2(g) for immediate use is advantageous in many bench-scale situations, eliminating the use of compressed H2(g). This is also significant in the context of less-experienced research participants. Herein, a simple two-chamber catalytic hydrogenation of 30 diverse substrates (aldehydes, α,β-unsaturated carbonyls, olefins, alkynes, nitro groups, azides, imines, aryl, and vinyl halides) and eight deprotections (N-Cbz and O-Bn) with Pd/C is described. H2(g) was obtained from the stable, storable, and easily handled NaBH4 and aq. CoCl2. Because of the ease of the procedure, eight deuteriation reactions were conducted using NaBD4 and CoCl2 in D2O. Some unusual outcomes in these reactions such as C–H bond activation/deuteriation, benzylic H/D exchange, di- and polydeuteriation have been analyzed and are reported.
Knyazev et al. (Mon,) studied this question.