Triacetic acid lactone, methylation

The natural pyrone yangonin (10) was synthesized by condensation of triacetic acid lactone methyl ether (8) with p-methoxybenzaldehyde (9) in the presence ol magnesium methoxide (prepared from 200 mg. magnesium and 10 ml. CH lOH)7... 

Thymine, methylation of, 256 Triacetic acid lactone, methylation of, 277-278... 

Chemoselective C-alkylation of the highly acidic and enolic triacetic acid lactone 104 (pAl, = 4.94) and tetronic acid (pA, = 3.76) is possible by use of DBU[68]. No 0-alkylation takes place. The same compound 105 is obtained by the regioslective allylation of copper-protected methyl 3,5-dioxohexano-ate[69]. It is known that base-catalyzed alkylation of nitro compounds affords 0-alkylation products, and the smooth Pd-catalyzed C-allylation of nitroalkanes[38.39], nitroacetate[70], and phenylstilfonylnitromethane[71] is possible. Chemoselective C-allylation of nitroethane (106) or the nitroacetate 107 has been applied to the synthesis of the skeleton of the ergoline alkaloid 108[70]. 

Divergent reports are available regarding the action of diazomethane on triacetic acid lactone (83). In the first investigations the sole formation of 6-methyl-2-methoxypyran-4-one (85) or of 6-methyl-4-methoxypyran-2-one (84) " w as reported. Later it was shown that a mixture of both compounds is formed albeit the 2-methoxy derivative (85) in small yield. The discrepancies are in... 

Hydroxy-6-methyl-2-pyrone (Triacetic Acid Lactone). 96... 

Methoxy-6-methyl-2-pyranone (1). Mol. wt. 140.13, m.p. 83-86°. Supplier Aldrich. This ether can be prepared by methylation of triacetic acid lactone (2) with dimethyl sulfate. Exposure of 2 to methyl fluorosulfonate produces the isomeric ether (3). ... 

Dimroth P, Greull G, Seyfferet R, Lynen F (1972) Hoppe Syler s Z Physiol Chem 353 126 Dimroth P,Ringelmann E, Lynen F (1976) Eur J Biochem 68 591 Bhogal P, Shoolingin-Jordan P. Incorporation of novel substrates into 6-methylsalicylic acid and triacetic acid lactone analogues by 6-methyl salicylic acid synthase. In Polyketides chemistry, biochemistry, molecular genetics. 1996. Royal Society of Chemistry, Bristol, UK, p 19... 

Methylation of Triacetic Acid Lactone with Diazomethane in Ether163... 

The methyl groups linked at C6 in compounds 2 and 21a exhibit the normal behavior of allylic positions and can be halogenated under radical conditions and oxidized by appropriate reagents. This is not true for 4-hydroxy compounds with a free C3 position, such as triacetic acid lactone... 

If no olefins are present, triacetic acid lactone 1 and its methyl ether 21a react photochemically to afford a mixture of compounds without pyrone structure (70CJC237, 70CJC2645). 

Since fatty acid and aromatic synthetases have many properties in common, it is interesting to consider the effect of omitting NADPH from incubations catalyzed by these enzymes and to examine the consequences. In all cases studied from animal (Bressler and Wakil, 1%2 Nixon et al., 1%8), yeast (Yalpani et al., 1969), and bacterial origin (Brock and Bloch, 1966), fatty acid synthesis is naturally abolished, but a Q compound, triacetic acid lactone (4-hydroxy-6-methyl-2-pyrone) (VII), is formed instead. This product is also made when the NADPH-requiring 6-methylsalicylate synthetase is deprived of this nucleotide (Dimroth et al., 1972), but the relative rate of synthesis is considerably greater than that produced by fatty acid synthetase in P. patulum (Yalpani et al., 1%9). However, Scott et al. (1971) have reported that triacetic acid lactone is also formed by 6-methylsalicylate synthetase, albeit at a reduced rate, even in the presence of NADPH. 

Reactions between triacetic acid lactone (MI-243) and ammonia or amines to give 4-hydroxy-6-methyl-2-pyridones are well known. For example, glycine and XII-243 give l-carboxymethylene-4-hydroxy-6-methyl-2-pyii-done. This latter 4-hydroxy-2-pyridone has also been formed from diketene and glycine in aqueous base via XU-244, which can be deacetylated in concentrated sulfuric acid. Dehydroacetic acid does not appear to be an intermediate in the formation of xn-244. Under these conditions it reacted with glycine to form an isomeric product, which, however, was not characterized. ... 

Hydroxy-6-methyl-2/f pyran-2-one Triacetic acid lactone C3H303 675-10-5 126.110 189 dec ... 

An intimate mixture of equimolar amounts of triacetic acid lactone and di-phenylcarbinol heated ca. 0.5 hr. at 150-160° in an oil bath -> 3-diphenylmethyl-4-hydroxy-6-methyl-2-pyrone. Y 67%. F. e. s. K.-H. Boltze and K. Heidenbluth,... 

Another type of pyridazine synthesis from pyrones involves coupling of the latter with diazonium salts and rearrangement of the intermediate hydrazones with either aqueous base or acid to pyrid-azinones. Thus, 4-hydroxy 6-methyl-2-pyrone (triacetic lactone) (44)... 

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