23702-49-0Relevant articles and documents
A Three-Step Synthesis of 4H-Cyclopenta[def]phenanthrene from Pyrene
Filippov, Dmitri V.,Overkleeft, Hermen S.,Schneider, Grégory F.,van der Ham, Alex
supporting information, p. 2013 - 2017 (2021/06/25)
4H-Cyclopenta[def]phenanthrene (CPP) is a valuable building block in the production of photoactive polymers, which find use in a wide range of organic electronic applications. Of particular importance is their use in the development of blue-colored, organic light-emitting diodes (OLEDs), which remains a challenge in the field. Unfortunately, commercial sources and synthetic procedures known in the literature are unable to provide enough CPP for large scale implementation. Herein, we report on the development of a novel, gram-scale synthesis of CPP in three steps, starting from pyrene. The key steps in our methodology are the ring contraction of pyrene-4,5-dione to oxoCPP in a single step, as well as the direct reduction of oxoCPP to CPP. Apart from the small number of synthetic steps, our methodology benefits from the use of relatively non-hazardous reagents, together with optimized purification procedures, making CPP accessible in useful quantities.
Intramolecular Cyclisations of Biphenyl-2-carboxyl Radicals: Evidence for a Π-State Aroyloxyl Radical
Glover, Stephen A.,Golding, Stephen L.,Goosen, Andre,McCleland, Cedric W.
, p. 842 - 848 (2007/10/02)
Biphenyl-2-carboxyl radicals generated by homolysis of acyl hypoiodites cyclise intramoleculary giving mainly δ-lactones through Ar2-6 cyclisation. 2'-Alkoxybiphenyl-2-carboxyl radicals do not give the expected Ar1-5 cyclisation product but undergo a homolytic ipso-substitution of the 2'-substituent.The phenanthrene-4-carboxyl radical gives 5H-phenanthropyran-5-one.Consideration of the molecular orbitals involved suggests that the biphenyl-2-carboxyl radicals are in the ?-ground state and have a higher energy, and, therefore, a less thermally accessible Σ-state than the corresponding amido-radicals.It is suggested that acyloxyl radicals which readily decarboxylate have either a Σ-ground state or a thermally accessible excited Σ-state.
