Picoline borane (PICB) was developed with the objective of enhancing the thermal stability of pyridine borane (PYB). The incorporation of the ortho methyl group not only imparts the desired stability to the reagents but also gives distinctive reactivity, particularly evident in the context of reductive amination. PICB demonstrates utility under neat conditions with liquid substrates; nonetheless, its solid state restricts its application with solid substrates. In a strategic effort to surmount this constraint, 5-Ethyl-2-methylpyridine borane (PEMB) was designed, introducing a bulky ethyl group at the 5-position of the pyridine ring. This structural modification results in a desired liquid state for PEMB and improves its resilience to elevated temperatures, water, and protic solvents.
Moreover, PEMB emerges as a promising candidate for substrates characterized by steric hindrance and electron deficiency.
