Photochemistry of 2-Nitroarenes: 2-Nitrophenyl-α-trifluoromethyl Carbinols as Synthons for Fluoroorganics

Abstract

Facile synthesis of a new series of 2,2′-bis(trifluoroacetyl) azoxybenzene derivatives and trifluoromethylated benzo[c]isoxazoline systems, along with trifluoroacetyl nitrosobenzene derivatives was achieved by solvent controlled photolysis of appropriate 2-nitrobenzyl alcohols. Corresponding photoactive 2-nitrobenzyl chromophore plays a distinct role in this photosynthetic process, while, quite unprecedented, pertinent fluoromethyl substitution leads to high value fluoromethylated products, whose direct access is not feasible by common synthetic protocols. The significance of fluorine and fluoroalkyl substitution and its prominent biological effects makes this new photochemical approach an important discovery in synthetic methodology. Plausible mechanistic pathways involved in the formation of the products during steady-state photolysis are further established by picosecond laser flash photolysis experiments.

Solvent dielectric delimited nitro–nitrito photorearrangement in a perylenediimide derivative

“…The stability of the nitrito isomer was found to be lower compared to that of the nitro isomer, and this result is in excellent agreement with the previously reported stabilities of nitrite linkage isomers. 29 The numerous possibilities of NA photochemistry in solvents with varying dielectric properties were well established by Mathew, Prakash and co-workers, 30 supporting the solvent dependency of photoisomerization observed in NO 2 -PDI. The never-ending interest in the excited-state properties of NAs mainly stems from the ultrafast dynamic branching of the singlet excited Franck–Condon state to either the triplet receiver or photoproduct states.…”

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

“…The photochemistry of nitroaromatic functional groups has a rich history that dates back decades [ 1 – 5 ]. Photochemical pathways allow access to diverse and interesting target structures [ 6 – 10 ], though photocleavage of C–X bonds for use as photoremovable protecting groups [ 11 – 12 ] has been the major thrust of the development of 2-nitroaryl compounds. Various 2-nitrobenzyl derivatives are used to photocage heteroatom functional groups, including alcohols, amines, carboxylic acids, and phosphates [ 11 ].…”

Structural characterization of the azoxy derivative of an antitubercular 8-nitro-1,3-benzothiazin-4-one

“…The simplest azoxybenzene structure is that of (Z)-azoxybenzene (TIHTEK; Gonza ´les Martı ´nez & Berne `s, 2007). The structure most related to that of 4, containing bicycles with fused sixmembered rings, appears to be that of (Z)-1,2-bis[2-(2,2,2trifluoroacetyl)naphthalen-1-yl]diazene oxide (XOZHUS; Belligund et al, 2019). In contrast to 4, in both TIHTEK and XOZHUS the aromatic rings are not coplanar and are significantly tilted out of the plane of the azoxy group.…”