Phloroglucinol acylation

Phenyl isocyanate, photoreactions of 1075 o-Phenylphenol, photodimerization of 1017 2-Phenylphenol 1350 photooxidation of 1084 Phenylpropanoids, Cl mass spectra of 293 Phenyl radicals 1100 Phloroglucinol, acylation of 631 thermochemistry of 247 Phosphates—see 1,3-Diphosphates Phosphatidylcholine liposomes 851 Photoacidity 491-494... 

A synthetic approach to hyperevolutin A 421, prenylated bicyclo[3.3.1] nonanone derivative, with an acylated phloroglucinol-type fragment, has been described (464). Intramolecular allene-nitrile oxide cycloaddition of 422 has been used to construct the bicyclic framework and the vicinal quaternary centers in cycloadduct 423. 

Derivatives. Many derivatives of acylated phloroglucinols that bear a benzene ring substituent or an ether or glycoside linkage occur in nature. Examples are cotoin [479-21-0] (52) in coto bark and conglomerone [480-25-1] (53) in Eucalyptus conglomerata. 

Based on published procedures for preparing both di- and tri-N-protected tert-butoxycarbonyl (Boc) cyclam derivatives [27], we developed the alternate procedure shown in Scheme 2 for obtaining the tri-branched species 11 [28] as well as related procedures for the new tri-branched derivative 12 (see Scheme 3) [28], the linearly linked derivative 13 [28] and the linked cyclic derivative 14 [29], In the case of the phloroglucinol derivative, tri-Boc protected cyclam was first acylated with chloroacetyl chloride the resulting chloromethylamide was then used to trialkylate phloroglucinol in DMF at 70 °C over caesium carbonate as outlined in Scheme 3. Subsequent... 

J9- Acyl phloroglucinol °C a-Iminoalkyl- mercaptoacetic acid hydrochloride °C... 

Constitution. Tautomerism.—The constitution of each of the poly-phenols which we have considered has not been taken up because it has been sufficiently established by the syntheses and reactions as given. In the case of phloroglucinol, however, we have another case of tautomerism. Its constitution as tri-hydroxy benzene is established by the syntheses given for it and the fact that it yields tri-acyl derivatives. Toward other reagents, however, it acts otherwise than as a hydroxyl compound. Hydroxylamine, H2N—OH, which is the characteristic reagent for aldehydes and ketones (p. 124), yields a... 

Unfortunately, modification of the aromatic nucleus to a phloroglucinol dimethyl ether system (92) adversely affected the ability of the phenolic hydroxyl to undergo acylation. This was found to be inconsequential however, since the acylated product derived from resorcinol monomethyl ether (93) was completely resistant to the intra-... 

More recently, the reaction of malonyl chloride with the enol ethers of cyclic alkenes to give 4,6-alkano-1,3,5-trihydroxybenzene systems in variable yields (18-70%)(ref.2) has been investigated. For example, the enolic methyl ether of cyclooctene gives with malonyl chloride the phloroglucinol depicted by acylation at the double bond and allylic position. 

All the natural a- and -acids have been synthesized. Phloroglucinol is first acylated to give the desired phloracylphenone (20), which is then alkylated... 

The biosynthesis of the hop resins occurs by similar routes. Experiments with radioactively labelled substrates have established that the phloroglucinol nucleus is formed from three molecules of acetic acid and not from sugars or shikimate. The acyl side-chains are formed from amino acids or intermediates in their biosynthesis. Thus, in humulone and lupulone they arise from leucine, in the co-analogues from valine, and in the ad-analogues from isoleucine. The amino acids themselves undergo transamination and decarboxylation to give... 

The Pechmann condensation served as a key ring-forming reaction in Xu and co-workers s synthesis of the HIV-1-selective nonnucleoside reverse transcriptase inhibitor calanolide A (39). In this work, phloroglucinol (35) and ethyl butyrylacetate (36) were condensed in sulfuric acid at 90 °C to provide 5,7-dihydroxy-4-propylcoumarin (37) in nearly quantitative yield on 150 g scale. Subsequent Friedel-Crafls acylation of 37 followed by condensation of the acylcoumarin product with 4,4-dimethoxy-2-methylbutan-2-ol provided pyranylcoumarin 38, which was converted to... 

Hop bitter acids and hyperforin are both derived from three different building blocks a branched short-chain CoA ester derived from amino acid metabolism and three C units derived from malonyl-CoA constitute the acyl phloroglucinol core, which carries two to several isopentenyl side chains that originate from terpenoid metabolism (Adam et al., 2002 Drawer and Beier, 1976 Goese et al., 1999 Karppinen et al., 2007). 

Preparation by Friedel-Crafts acylation of phloroglucinol trimethyl ether with benzoyl chloride in the presence of aluminium chloride [753], in ethyl ether for 8 h [416]. 

Also obtained by Friedel-Crafts acylation of phloroglucinol with o-orsellinic... 

Oil Preparation by two successive Friedel-Crafts V / —/ acylations of phloroglucinol, first with acetic... 

Preparation by Friedel-Crafts acylation of 1,3-dime-thyl-phloroglucinol with acetic acid in the presence of boron trifluoride (63%) [3116],... 

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