Abstract:Für eine Struktur‐Wirkungs‐Untersuchung werden potentiell antianaphylaktisch aktive (PCA‐Test) 2′‐ und 6‐Carboxyflavonolderivate mit planarer Fixierung des B‐Rings ‐ 2‐substituierte 6,13‐Dehydropeltogynan‐11,14‐dione ‐ und mit nicht ebenem Molekülbau −6‐substituierte 2′‐Carboxyflanonole ‐ synthetisiert.
“…[7b,8, [22][23][24][25][26][27] The desired aminoflavones (i.e., 4) can be obtained by reduction or hydrolysis. The latter transformation usually requires harsh conditions (Scheme 2).…”
Thiol–ene “click” chemistry has emerged as a powerful strategy to construct carbon–heteroatom (CS) bonds, which generally results in the formation of two regioisomers. To this end, the neutral ionic liquid [hmim]Br has been explored as a solvent cum catalyst for the synthesis of linear thioethers from activated and inactivated styrene derivatives or secondary benzyl alcohols and thiols without the requirement of using a metal complex, base, or free radical initiator. Furthermore, detailed mechanistic investigations using 1H NMR spectroscopy and quadrupole time‐of‐flight electrospray ionization mass spectrometry (Q‐TOF ESI‐MS) revealed that the “ambiphilic” character of the ionic liquid promotes the nucleophilic addition of thiol to styrene through an anti‐Markovnikov pathway. The catalyst recyclability and the extension of the methodology for thiol–yne click chemistry are additional benefits. A competitive study among thiophenol, styrene, and phenyl acetylene revealed that the rate of reaction is in the order of thiol–yne>thiol–ene>dimerization of thiol in [hmim]Br.
“…[7b,8, [22][23][24][25][26][27] The desired aminoflavones (i.e., 4) can be obtained by reduction or hydrolysis. The latter transformation usually requires harsh conditions (Scheme 2).…”
Thiol–ene “click” chemistry has emerged as a powerful strategy to construct carbon–heteroatom (CS) bonds, which generally results in the formation of two regioisomers. To this end, the neutral ionic liquid [hmim]Br has been explored as a solvent cum catalyst for the synthesis of linear thioethers from activated and inactivated styrene derivatives or secondary benzyl alcohols and thiols without the requirement of using a metal complex, base, or free radical initiator. Furthermore, detailed mechanistic investigations using 1H NMR spectroscopy and quadrupole time‐of‐flight electrospray ionization mass spectrometry (Q‐TOF ESI‐MS) revealed that the “ambiphilic” character of the ionic liquid promotes the nucleophilic addition of thiol to styrene through an anti‐Markovnikov pathway. The catalyst recyclability and the extension of the methodology for thiol–yne click chemistry are additional benefits. A competitive study among thiophenol, styrene, and phenyl acetylene revealed that the rate of reaction is in the order of thiol–yne>thiol–ene>dimerization of thiol in [hmim]Br.
“…In this paper, we report on the synthesis of 8-bromoflavone (6) starting from the commercially available 2-bromophenol (10) and its Buchwald-Hartwig reaction with some aliphatic and aromatic amine derivatives.…”
Section: Syn Thesismentioning
confidence: 99%
“…The esterification of 2-bromophenol (10) with acetyl chloride in the presence of triethylamine provided 2-bromophenyl acetate (9) in excellent yield (98%). After the first Fries rearrangement experiment of ester 9, which was carried out under the usual neat conditions, revealed that optimization is required because the reaction resulted exclusively in 3′-bromo-4′-hydroxyacetophenone (11) and only traces of the desired 3′-bromo-2′-hydroxyacetophenone (8) was formed (Scheme 3).…”
Section: Scheme 2 Retrosynthesis Of 8-bromoflavone (6)mentioning
confidence: 99%
“…However, synthesis of aminoflavones suffer from limitations, especially in the case of derivatives linked to their amine substituents at ring A. The most common synthetic methods are based on Baker-Venkataraman rearrangement 9,10 or Claisen-Schmidt condensation 11,12 (Scheme 1).…”
Simple and convenient synthesis of 8-bromoflavone was achieved, starting from 2-bromophenol through 3′-bromo-2′-hydroxyacetophenone whose preparation was managed to be solved by optimized Fries rearrangement. The Buchwald-Hartwig reaction of 8-bromoflavone with different type of primary and secondary amines was carried out.
“…In our search for antiasthmatic drugs we became therefore interested in the development of CysLT 1 receptor antagonists. , Our attempts to find new lead structures for CysLT 1 receptor antagonists started with the synthesis of carboxylated flavonoids, compounds which are known for their antianaphylactic properties. − We found two new lead structures, 1 and 2 (Scheme ), which showed weak but significant affinities for the CysLT 1 receptor having K D values of 1.11 ± 0.14 × 10 -5 and 1.48 ± 0.28 × 10 -5 M, respectively. 2 Optimization of Lead Structure 1 …”
The synthesis and CysLT1 antagonistic activities of a new series of 2-, 3-, and 4-(2-quinolinylmethoxy)- and 3- and 4-[2-(2-quinolinyl)ethenyl]-substituted, 2'-, 3'-, 4'-, or 5'-carboxylated chalcones are described. Structure-activity relationship studies indicate a preference for the presence of a negatively charged (acidic) moiety, although in some cases nitrile or ester analogues also exhibit moderate activity. The quinoline moiety may be substituted at either the 3- or the 4-position. Replacement of this heterocycle by other aromatic groups results in compounds with comparable affinities [2-(7-chloroquinoline), 1-(1-methyl-2-benzimidazole), or 1-(2-benzothiazole)] or substantially lower activities [1-(1-ethoxyethyl)-2-benzimidazole, 2-naphthyl, or phenyl]. The quinoline and chalcone moieties may be connected by either an ethenyl or a methoxy spacer. The acidic moiety at the chalcone B ring may be attached to the 2'-, 3'-, 4'-, or 5'-position, for both the 3- and 4-substituted chalcones. There are no general patterns to specify which substitution positions gave the most potent compounds. The series contains several potent CysLT1 receptor antagonists, with K(D) values approaching the nanomolar range, as measured by the displacement of [3H]LTD4 from guinea pig lung membranes. Antagonism of LTD4-induced contraction of guinea pig ileum, the inhibition of antigen-induced contraction of guinea pig trachea in vitro, and the inhibition of LTD4-induced increase of vascular permeability in vivo are determined for chalcones with high CysLT1 receptor affinities (K(D) values below 0.1 microM). 2'-Hydroxy-4-(2-quinolinylmethoxy)-5'-(5-tetrazolyl)chalcone (14, VUF 4819) showed good activity in both in vitro and in vivo assays and has been selected for further evaluation.
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