Pyridine and Its Derivatives

Ionization of pyridine: Interplay of orbital relaxation and electron correlation

“…An important distinction between the relaxation mechanism in the 7a 1 (4) scheme, the proper implementation of which is still not available.…”

“…Hence, an understanding of the electronic structure of pyridine is essential to many fields of organic chemistry including biochemistry, medicinal and pharmaceutical chemistry. 1,2 Photoelectron spectroscopy, especially when carried out with a continuously tunable photon source, provides an ideal means of exploring molecular electronic structure. The results obtained from such experiments can be interpreted with the help of quantum chemical calculations.…”

Lithium, sodium and potassium picolyl complexes: syntheses, structures and bonding

“…3 There are of course a plethora of different methodologies available to the synthetic chemist for the 25 introduction of a pyridine ring into the construction of such a molecule, the particular methodology of choice depending on factors such as the desired substitution on the ring or the ring position which is to be functionalized. One access point which drew our interest as group 1 metallation chemists was the 30 lithiation and subsequent electrophilic quenching of methylpyridine (picoline).…”

Alkylation of Pyridines at Their 4‐Positions with Styrenes plus Yttrium Reagent or Benzyl Grignard Reagents

“…For example, nucleophilic addition of organometallic reagents to pyridines takes place mostly at their 2-or 4-positions, among which the former appears more feasible, but the selectivity is often difficult to control. [1][2][3][4][5] A similar issue is also found in the alkylation of pyridines through CÀH bond activation, in which the reaction preferentially occurs at the 2-position of pyridines, [11,12] likely facilitated by the initial interaction between the metal reagents and the pyridine nitrogen. Thus, the highly regioselective substitution of pyridines at the 4-position has been less frequently encountered [4,5,12] and still calls for newer, simpler, or more dependable methods using inexpensive reagents.…”

“…[1] Their synthetic methods rely on traditional reactions include nucleophilic [1][2][3][4][5][6] or radical [1,7] additions to pyridines, metalation of pyridines, [1,8] and multicomponent coupling reactions from acyclic starting materials. [1,9] In addition to these, new syntheses through CÀH bond activation of pyridines have recently appeared. [10][11][12] When the synthesis starts with pyridines, an issue on the regioselection and its selectivity for the introduction of a side chain or a functional group arises.…”