Synthesis of 6‐Acetyl‐3‐alkyl‐2‐phenyl‐chromen‐4‐ones by Phasetransfer Catalysed Baker‐Venkataraman Reaction
Three of the five partial steps of the Baker‐Venkataraman xssynthesis of flavones (scheme 1) can be favoured by PTC conditions. In the intermolecular O‐acylations of the 4‐hydroxyacetophenone 1 (A) and the 5‐acetyl‐2‐hydroxy‐acylophenones 3 (C), respectively, the nucleophilicity of the phenolat anions is increased by the PT catalysator. The steric and electronic effects of the substituents in the 5‐acetyl‐2‐benzoyloxy‐acylophenones 4 cause the formation of the 6‐acetyl‐flavones 6 in the phasetransfer catalysed Baker‐Venkataraman rearrangement (D) in one step and in good yields. The over‐all yields of the 1 → 6 reactions are not higher than 30% because of the limiting step (B). This Fries rearrangement of 4‐acyloxy‐acetophenones 2 affords only 32–62% of 3 under drastically enhanced conditions.
A Townsend‐Huxley apparatus has been used to measure the lateral diffusion coefficient to mobility ratio D/μ in two gas mixtures of special interest when modeling h.p. CO2 lasers. The results are compared with the corresponding theoretical values obtained with the conventional two‐term theory in order to assess the limits of the theoretical predictions and have indications on the accuracy of the available cross sections.
According to the Institute of Medicine, 116 million Americans suffer from chronic pain, costing over $500 billion annually. As such, the use of pain‐killing drugs like morphine and oxycodone has increased dramatically over the past decade. Analgesic effects are produced through agonism, or activation, of the body's mu (MOR) and delta (DOR) opioid receptors, which are G‐coupled protein receptors. Tolerance, the decreased analgesic effect of MOR agonists after prolonged use, is a major problem facing opioid pain management. A drug that antagonizes, or inhibits, DOR can greatly reduce the development of tolerance to MOR agonists, offering new pain therapy potentials. One example of a selective DOR antagonist is naltrindole (NTI), which has a similar structure as morphine, except for a cyclopropylmethyl group on its nitrogen substituent and a bulky indole group. The large indole ring negatively interacts with the W318 residue on MOR but is able to bond with W284 residue on the DOR, producing DOR‐selective antagonism. Co‐administration of NTI with morphine represents a potential new approach to producing analgesics with less tolerance. Understanding the structure of this ligand and enzyme may further structure‐based drug designs. The Marquette University High School SMART Team (Students Modeling A Research Topic) modeled naltrindole bound to DOR using 3‐D printing technology. Supported by a grant from the NIH‐CTSA.
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