Synthesis of Polycyclic Aromatic Hydrocarbons (PAHs) via a Transient Directing Group

Abstract

In this work, an efficient synthetic route was developed to construct PAHs with diverse shape, width, and edge topology. The precursors of PAHs were obtained by using a direct arylation of arenes via a transient ligand-directed C−H functionalization strategy and the cycloaromatization was readily achieved by using a Brønsted acid catalyst. This novel route provides an opportunity to build up PAHs in a highly efficient manner.

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

“…Very recently, Zhang reported an example of Pd‐catalyzed ortho ‐C(sp 3 )−H arylation of benzaldehydes with aryl diiodides with the transient ligand L21 to construct the precursors of polyaromatic hydrocarbons (PAHs). The sequential intramolecular cationic cyclization and dehydration was demonstrated in the preparation of PAHs with good yields by employing TfOH as a Brønsted acid catalyst (Scheme ) …”

Transient imine directing groups for the C–H functionalisation of aldehydes, ketones and amines: an update 2018–2020

“…Yi and Zhang reported a method to construct polyaromatic hydrocarbons from o-tolualdehydes and di/tri-iodoarenes (Scheme 13a). 43 While similar to earlier work by Kim, 44 this method used a simple and commercial TDG (glycine) to access a broader range of polycycle aromatic hydrocarbons in higher yields. Diiodoarenes with 1,2-, 1,3-, and 1,4-substitution along with 1,3,5-triiodoarenes could be used successfully to construct di/trialdehyde products which were then cyclised by treatment with triflic acid to give polyaromatic products.…”

“…The activation of benzylic C(sp 3 )-H has seen some key advances in the past two years, with both new directing groups and novel coupling partners being reported. [43][44][45][46][47][48][49][50] The benzylic C-H bonds are electronically activated by the presence of the aryl group, and are relatively constrained geometrically. Yi and Zhang reported a method to construct polyaromatic hydrocarbons from o-tolualdehydes and di/tri-iodoarenes (Scheme 13a).…”

Clar Covers of Overlapping Benzenoids: Case of Two Identically-Oriented Parallelograms

“…Benzenoid hydrocarbons are an intensively studied class of aromatic molecules attracting attention of scientists specializing in various fields of chemistry including organic synthesis [1,2] and characterization [3][4][5], combustion chemistry [6,7], nanoscience [8,9], atmospheric chemistry [10,11], astrochemistry [12,13], computational chemistry [14,15], and chemical graph theory [16,17]. Enumeration and construction of Clar covers for benzenoid hydrocarbons constitutes one of the important branches of chemical graph theory.…”

“…In the first case, the multiset of interface bonds covering orders consists of o µ 1s and one 0; the distinction between Clar covers belonging to this category concerns the location of the single bond. Similarly, in the second case, the multiset of interface bonds covering orders consists of o µ − 1 1s and two 1 2 s with the distinction between Clar covers belonging to this category concerning the location of the two consecutive aromatic bonds. Each of these 2 o µ + 1 partitions generates a system of fixed bonds in MvM not limited only to interface i n 2 +m 2 −ν but extending through both overlapping parallelograms.…”