2pyridyl

2-pyridyl is a substituent derived from pyridine in which the ring is attached to another fragment at the 2-position, giving the pyridin-2-yl group. It is commonly written as 2-pyridinyl or pyridin-2-yl in IUPAC terminology. The term is used in organic and organometallic chemistry to denote a heteroaryl moiety that retains the ring nitrogen and provides a single point of attachment at C-2.

Structure and properties: The 2-pyridyl group is a pyridine ring with a free valence at the 2-position. Like pyridine, the ring contains a basic, sp2-hybridized nitrogen that can donate a lone pair to metals or participate in coordination. Substitution at the 2-position influences the steric and electronic environment of the ring, which in turn affects reactivity in cross-coupling, coordination chemistry, and catalysis. The group is typically a weakly basic, N-donor ligand when bound to metal centers.

Applications: 2-pyridyl substituents are widely used as ligands in coordination chemistry and organometallic catalysis. The lone-pair donation from the pyridine nitrogen enables metal binding, and the 2-pyridyl framework can participate in the formation of complex structures and active catalysts. In synthetic chemistry, 2-pyridyl fragments are installed via cross-coupling reactions of 2-halo pyridines (for example, 2-bromopyridine) or via directed lithiation of pyridine followed by electrophilic trapping. The motif also appears in various bioactive and pharmaceutical compounds as part of more complex heteroaryl frameworks.

See also: pyridine, pyridinyl, pyridin-2-yl ligands.