Electrophilic Substitution of Monosubstituted Pyrenes

Abstract

Bromination and the Friedel–Crafts acetylation of monosubstituted pyrenes were examined. Acetylation of 1-acetyl- and 1-ethylpyrene occurred at the 8-, 6-, or 3-position, but the reaction of 1-methoxypyrene afforded only the 8- and 6-acetyl derivatives. By acetylation, 4-acetylpyrene yielded the 1- and 6-acetyl compounds, and 4-ethylpyrene gave the 6- and 8- derivatives. Also, 4-bromopyrene afforded the corresponding 8-, 6-, and 1-acetyl derivatives by the same reaction. Bromination of 1-ethyl- and 4-ethylpyrene yielded the 8- and 6-bromides, but the reaction of 1-nitro- and 1-bromopyrene took place at the 6-, 8-, or 3-position. The formation ratio of these regioisomers differs by the substituents. The regioselectivity on the acetylation accords in some degree with the prediction based on the 13C NMR chemical shift of each position. The relative rates of these electrophilic substitutions correlate to the substituent constant, σ+, of the substituent attached to the pyrene.

Synthesis of 5‐(2‐Pyrenyl)‐2′‐deoxyuridine as a DNA Modification for Electron‐Transfer Studies: The Critical Role of the Position of the Chromophore Attachment

“…Standard electrophilic substitution of pyrene (3) produces mainly derivatizations in the 1-position and subsequently 1,3-, 1,6-and 1,8-disubstituted products. [25] Pyrenes that are substituted in ring position 2 are difficult to obtain. The most convenient synthetic strategy for the introduction of functional groups in the 2-position involves the conversion of pyrene (3) into 4,5,9,10-tetrahydropyrene by catalytic hyScheme 1.…”

Detection of Mutagenic 1-Chloro-3-, -6-, and -8-Nitropyrenes in Surface Soil Collected in Kyoto, Japan

“…16) Chemical shifts of peaks 2, 3 and 4 were very similar to those of 1,6-, 1,8-and 1,3-BNPs, respectively. This result also shows that peaks 2, 3 and 4 were due to 1,6-, 1,8-and 1,3-CNPs, respectively.…”

Non-K Region Disubstituted Pyrenes (1,3-, 1,6- and 1,8-) by (Hetero)Aryl Groups—Review

“…It is related to the difficulty of substitution of the pyrene structure due to the preference for electrophilic substitution at the 1,6- and 1,8- positions rather than the 1,3-positions of pyrene. The determined spectroscopy yield of that isomer that is present as a byproduct of the bromination reaction equals 3% [36]. It causes that the substitution at positions 1 and 3 is only possible by the multistep reactions with the number of intermediates that contain the protecting groups at 7-position.…”