3,3′,5,5′-Tetra-tert-butyl-4,4′-diphenoquinone (DPQ)-Air as a New Organic Photocatalytic System: Use in the Oxidative Photocyclization of Stilbenes to Phenacenes

Abstract

We report an organic photocatalytic system, namely 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone (DPQ) and air, capable of coupling efficiently with the photocyclization of stilbenes to afford phenacenes. The potential of this new and mild process is shown with the synthesis of [5]-and [7]phenacene, two semiconductors recently implemented into organic electronic devices, with high yields and remarkable purity.

A Practical Synthesis and X-Ray Crystal Structure of (E)-4-(1-naphthylvinyl)pyridine and Related Compounds

“…Initial attempts to synthesize (E)-4-(1-naphthylvinyl)pyridine ((E)-4-1-nvp, 1) followed literature procedure [8] and utilized a Wittig olefination (Scheme 1-b-i), wherein 1-(chloromethyl)naphthalene was refluxed with triphenylphosphine in toluene. This Synthesis of the HWE phosphonate precursor followed a modified literature procedure, [27] wherein 1-(chloromethyl)naphthalene was refluxed in a stoichiometric amount of triethyl phosphite (Scheme 1-b-iv). This gave diethyl 1-naphthylmethyl phosphonate in excellent yield (96%) and did not require further purification before proceeding to the next synthetic step.…”

Regiospecific Photochemical Synthesis of Methylchrysenes

“…3-Methylchrysene (3b) was made by the Mallory reaction in 69% yield after 24 h irradiation [19], and later as a 2.5 g batch in 1 L of cyclohexane in 79% yield after 3 h irradiation with a 400 W high pressure mercury lamp [20] (Scheme 1c). 1-Methylchrysene (3a) was made only recently, in a flow system with plugs of air at 100 mg-scale in 89% yield [21,22], while Carrera et al [23] used a regular immersion well photoreactor with DPQ/air to obtain 3a in 49% yield (Scheme 1d).…”

“…Numbering of substituent positions are shown in the products. (a) [15], (b) [18], (c) [19,20], (d) [21][22][23]. [15], (b) [18], (c) [19,20], (d) [21][22][23].…”

Synthesis of Phenacene–Helicene Hybrids by Directed Remote Metalation

“…Apart from the general methods reported for the preparation of PAHs, , representative examples of the recent approaches include cross-couplings followed by metal-catalyzed intramolecular cyclizations, − C–H activation, , oxidative alkene arylation of o -aryl styrenes, , photochemical cyclizations, − directional synthesis using transient directing groups, π-annulation reactions, APEX (annulative π-extension) reactions, from cycloaddition reactions of aryne precursors, − alkyne [2 + 2 + 2] cycloisomerizations, − and Diels–Alder reactions , among other protocols. − …”