Novel 1,4,5,8‐Phenanthrenediquinones and Unusual Deoxygenation with Trimethylsilyl Iodide

Abstract

Attempt for aryl methyl ether cleavage of 5,8-dimethoxy-1,4-phenanthrenequinone (4) with boron trichloride or tribromide resulted in the halogenation of the quinone double bond to form 5a,b. Surprisingly, reaction of dimethyl ether 4 with trimethylsilyl iodide afforded the phenanthrenediquinone 6, whereas deoxygenation to 8 and 9 occurred by reaction of trimethylsilyl iodide with derivative 7. The phen-

Attempted characterisation of phenanthrene-4,5-quinone and electrochemical synthesis of violanthrone-16,17-quinone. How does the stability of bay quinones correlate with structural and electronic parameters?

“…A geometry optimisation on the singlet PES resulted in optimisation of quinone 18. 16 Considering quinone 20/peroxide 23, it is the peroxide tautomer 23 that contains the larger number of Clar sextets (20 : 2; 23 : 4). Consistent with energies, yet there is some variation.…”

Designing high-voltage carbonyl-containing polycyclic aromatic hydrocarbon cathode materials for Li-ion batteries guided by Clar's theory

“…These designed molecules have positive DC 2Li and are predicted to have high energy density, but currently they have not been synthesized experimentally; hereaer, we managed to nd an experimentally available molecule with positive DC 2Li , PADQ (9), and preliminarily investigated its electrochemical behaviors as the cathode material for LIBs (detailed information about the synthesis, characterization and electrochemical measurement of PADQ is presented in the ESI †). PADQ is a moiety of a natural product in Dendrobium moniliforme 59 and has been synthesized by Krohn et al 51,52 The Clar structure of PADQ has one Clar sextet, and aer lithiation, the number of Clar sextets increases to two. The theoretical capacity of PADQ is 403 mA h g À1 , its DC 2Li value is 0.5, and the calculated average voltage by DFT is 2.63 V, giving rise to a theoretical energy density of 1060 W h kg À1 (Fig.…”

“…47,48 Fig.1 shows the comparison between the calculated and the experimentally measured voltages for a series of organic molecules, demonstrating the reliability of our computations. PADQ was synthesized by following the procedures in previous reports, 51,52 Atomic charges were calculated by using natural bond orbital (NBO) method, 49 and atomic charge differences were calculated by taking the difference of atomic charges of the neutral and the doubly charged molecules.…”

“…NICS(1) zz , the out-ofplane zz tensor component of the NICS value computed at 1 Å above ring centers, which well correlates with the aromatic stabilization energies for planar p-rings, 50 was used to evaluate the aromaticity. PADQ was synthesized by following the procedures in previous reports, 51,52 and the detailed synthetic processes are shown in the ESI. † Electrochemical performances were evaluated in CR2025-type coin cells assembled in an argon-lled glovebox.…”

Lessons Learned During Spiroketalization Experiments: Progress and Setbacks in the Preparation of Oxygenated Rubromycins and Synthesis of 3′‐Deoxyheliquinomycinone

“…The predominant formation of 46 was surprising, as the Li group reported the clean deoxygenation of a similar substrate to its respective spiroketal during their formal total synthesis of γ‐rubromycin. [3d] Strikingly, the electron‐rich naphthalene portion of these substrates additionally experienced a reduction at C‐8, presumably through protonation of the aromatic framework, followed by hydride addition and rearomatization through elimination of MeOH . In light of this disappointingly low‐yielding reaction sequence ( 29 → 30 → 45 , 5.8 % over two steps), we decided to abandon this “deoxygenation approach” towards the natural product γ‐rubromycin.…”