Our results therefore show that estrogen formation in the brain occurs with the same stereospecificity of hydrogen loss at C1 and C2 as in placental microsomes
Nuclear accumulation of estradiol derived from the aromatization of testosterone is inhibited by hypothalamic beta-receptor stimulation in the neonatal female We previously reported that hypothalamic beta-adrenergic receptor stimulation prevents testosterone (T)-induced androgenization (defeminization) of the female neonatal rat hypothalamus. It was hypothesized that hypothalamic beta-receptor stimulation blocks androgenization by reducing the nuclear accumulation of estradiol (E2) derived from the aromatization of T. Various adrenergic agonists and antagonists were injected intracerebrally in 4-day-old female rats. [3H] T and its 3H-metabolites (including E2) were extracted from hypothalamic nuclear pellets, and separated from one another with thin-layer chromatography and/or Celite chromatography. The ratio of recovered [3H] T and E2 in the control groups was arbitrarily assigned as a 100% conversion and nuclear accumulation. Phenoxybenzamine, an alpha-antagonist, and isoproterenol and isoxsuprine, beta-agonists, inhibited the nuclear accumulation of E2 to 66%, 69% and 85% of control, respectively.
A nonadrenergic, specific, competitive aromatase inhibitor, 1,4,6-androstratrien-3,17-dione (ATD) inhibited aromatization (and subsequent nuclear accumulation) to 39% of control. The beta-antagonist, hydroxybenzylpindolol, specifically prevented the inhibition of nuclear accumulation produced by phenoxybenzamine, isoproterenol and isoxsuprine, but did not alter the inhibition of aromatization produced by ATD. These studies support the hypothesis that beta-receptor stimulation prevents androgenization of the brain by inhibiting either the aromatization of T to E2 or the nuclear Photochemistry Driven by Excited-State Aromaticity Gain or Antiaromaticity Metabolism BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden.Gain of aromaticity or relief of antiaromaticity along a reaction path are important factors to consider in mechanism studies. Analysis of such changes along potential energy surfaces has historically focused on reactions in the electronic ground state (S0 ), but can also be used for excited states. In the lowest ππ* states, the electron counts for aromaticity and antiaromaticity follow Baird's rule where 4n π-electrons indicate aromaticity and 4n+2 π-electrons antiaromaticity. Yet, there are also cases where Hückel's rule plays a role in the excited state.
The electron count reversals of Baird's rule compared to Hückel's rule explain many altered physicochemical properties upon excitation of (hetero)annulene derivatives. Here we illustrate how the gain of excited-state aromaticity (ESA) and relief of excited-state antiaromaticity (ESAA) have an impact on photoreactivity and photostability. Emphasis is placed on recent findings supported by the results of quantum chemical calculations, and photoreactions in a wide variety of areas are covered.Designed metal-organic π-clusters combining the aromaticity of the metal cluster and ligands for a third-order nonlinear optical response.the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, The pivotal role of clusters and aromaticity in chemistry is undeniable, but there remains a gap in systematically understanding the aromaticity of metal-organic clusters. Herein, Seebio Light-Activated Acid Producer presents a novel metal-organic π-cluster, melding both metal-organic chemistry and aromaticity, to guide the construction of structurally stable Os-organic π-clusters. An in-depth analysis of these clusters reveals their bonding attributes, π-electronic composition, and origins of aromaticity, thereby confirming their unique metal-organic π-cluster properties.
Furthermore, the Os5 cluster exhibits a promising third-order nonlinear optical (NLO) response, attributable to its narrow band gap and uniform electron/hole distribution, suggesting its potential as an optical switching material. This research introduces a fresh perspective on clusters, centered on delocalization, and broadens the domain of aromaticity studies. It also presents a novel method for designing efficient third-order NLO materials through consideration of the structure-activity relationship.Aromaticity-promoted C-F Bond Activation in Rhodium Complex: A Facile Collaborative Innovation, Center of Chemistry for Energy Materials (iChEM), and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fluorine is the most electronegative element in the periodic table. Thus, activation of the carbon-fluorine (C-F) bond, the strongest single bond to carbon, has attracted considerable interest from both experimentalists and theoreticians. In comparison with numerous approaches to activate C-F bonds, the aromaticity-promoted method is less developed. Herein, we demonstrate that the C-F bond activation could be achieved by a facile tautomerization, benefitting from aromaticity, which can stabilize both the transition states and products.
6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid in Medicinal Chemistry of aromaticity in the C-F bond activation, providing experimentalists with an alternative approach to activate © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
