Rare Nitrene Insertion Followed by Redox Dimerization During the Photolysis of ‘Azido-meta-Meconine’

Abstract

Abstract
Aryl Azides are ‘green’ reagents and provide a fascinating area of chemistry and have many uses
in industry as pharmaceutical agents. Azidothymidine (AZT) is used to treat HIV-AIDS and a “2
dimethylaminoethyl azide (DMAZ)” is a powerful explosive. The ‘click’ reaction based on these
was awarded the coveted Nobel Prize in 2022, ‘click’ reaction is a ‘green’ regiospecific reaction
since atom efficiency is very high as no atom loss occurs. Reactions of azides involve many
unusual and fascinating transition states and intermediates.
In this paper, we discuss the photochemistry of ‘Azido-meta-Meconine’. Photolysis at 50C using
wavelength of 254 nm for 6 hr was carried out. The reaction product was subjected to preparative
Thin Layer Chromatography (TLC), two bands namely an ‘Upper band’ and a ‘Lower band’ were
separated, molecular weight values in LC- MS spectrum differs from each other by six atomic
mass units (six hydrogens). One part of the reactive intermediate underwent addition of hydrogen
(reduction) and other dehydrogenation (oxidation) which thus constitutes a rare example of
dimerization of nitrene intermediate previously unknown in the literature. Detailed LC-MS studies
provided evidence for the formation of two products with yield around 94.99 %, which is a very
unusually high yield in such a photochemical reaction. Further spectroscopic studies (UV-Visible,
FT-IR, 1H-NMR etc.) were also done for corroborating the successful formation of these two
products.