α-Picoline-borane, 2-Methylpyridine borane, PICB
Pic-BH3 is a very stable solid that can be stored without noticable decomposition. This reagent is an excellent alternative for reductive aminations in methanol, water, or even under solvent-free conditions.
Recent Literature
A mild and efficient one-pot
reductive amination of aldehydes and ketones with amines using
α-picoline-borane as a reducing agent in the presence of small amounts
of AcOH is described. The reaction has been carried out in MeOH, in H2O,
and in neat conditions. This is the first successful reductive amination
in water and in neat conditions.
S. Sato, T. Sakamoto, E. Miyazawa, Y. Kikugawa, Tetrahedron, 2004, 60, 7899-7906.
Reductive aminations of shelf-stable bisulfite addition compounds of
aldehydes can be run under aqueous micellar catalysis conditions with readily
available α-picolineborane as the stoichiometric hydride source. Recycling
of the aqueous reaction medium is easily accomplished.
X. Li, K. S. Iyer, R. R. Thakore, D. K. Leahy, J. D. Bailey, B. H. Lipshutz, Org. Lett., 2021, 23,
7205-7208.
Half-sandwich ruthenium complexes activate terminal alkynes toward
anti-Markovnikov hydration and reductive hydration under mild conditions.
Propargylic alcohols can be converted to 1,3-diols in high yield and with
retention of stereochemistry at the propargylic position. The method is also
amenable to formal anti-Markovnikov reductive amination and oxidative hydration
reactions to access linear amines and carboxylic acids, respectively.
M. Zeng, S. B. Herzon, J. Org. Chem.,
2015,
80, 8604-8618.
An efficient method for the direct reductive alkylation of hydrazine derivatives
with α-picoline-borane provided various N-alkylhydrazine derivatives upon
fine-tuning of the substrates and the reagent equivalency in a one-pot manner.
The method was applied to the synthesis of active pharmaceutical ingredients of
therapeutic drugs such as isocarboxazid.
Y. Kawase, T. Yamagishi, J.-y. Kato, T. Kutsuma, T. Kataoka, T. Iwakuma, T.
Yokomatsu, Synthesis, 2014, 46,
455-464.
