7- -tetrones, formation

Pteridine-2-sulfonic acid, 4-oxo-3,4-dihydro-synthesis, 3, 300 Pteridine-2,4,6,7-tetrone formation, 3, 308 reactions, 3, 296 synthesis, 3, 291... 

It is assumed that in the formation of 2-509, a Knoevenagel condensation of the benzaldehydes 2-511 and tetronic acid 2-512 initially takes place, and this is followed by the generation of a hemiaminal with the aniline 2-510 and an electrophilic substitution. 

The reaction of a nitrile with a Reformatsky reagent is known as the Blaise reaction and when applied to (9-trimethylsilyl cyanohydrins leads to the formation of tetronic acids with high ee [79]. By working-up the Blaise reaction with ammonium chloride it is possible to isolate... 

The O-antigens of Brucella species are homopolymers of a-l,2-linked 4,6-dideoxy-4-formamido-D-mannopyranose residues in which there may bea-1,3 linkages [102,103], The Yersinia 0 9 antigen is a similar 1,2-linked homopolymer but contains no 1,3 linkages. A related structure Y-acylated by 3-deoxy-L-glycero-tetronic acid in place of the formate group is produced by Vibrio cholerae Inaba and Ogawa strains [104], These structures have been the subject of synthetic work [105-107],... 

It can be prepared by treatment of 3-amino-2//-azirines (e.g. 3-(dimethyl-amino)-2,2-dimethyl-2//-azirine) with an amino acid or peptide and, finally, with a (u-hydroxyacid. The formation of the oxazolone, VI/121, is observed when VI/120 is treated with acid. The ring enlargement step, the conversion of VI/121 to VI/122, is observed under the same conditions. The transformation of (-)-(R,R)2- 2-[2-(2-hydroxy-2-phenylacetamido)-2-methylpropionato]-2-phenylacetamido -N,N,2-trimethylpropionamide (VI/123) to (-)-(R,R)-3,3,9,9-tetramethyl-6,12-diphenyl-l,7-dioxa-4,10-diazacyclododecane-2,5,8,ll-tetrone (VI/126) in dry toluene/hydrochloric acid at 100° was observed in a 88 % yield. Compounds VI/124 and VI/125 are discussed to be intermediates. In an analogous reaction sequence cyclopeptides can be synthesized [93]. 

Figure 6 Formation of tetronic acids from B-ether type of structures by ozonation.

Three-components reaction of an aldehyde, enamine 31 and tetronic acid 310 in glacial acetic acid under MW irradiation without a catalyst gave the furoquinolines 309 (06S3874), via the formation of the arylidene derivative 311 (Scheme 58). 

Reaction of cyclic lactams with diazomethane is supposed to involve deprotonation in the first step. Treatment of (219) with diazomethane leads to the formation of A-methylated products (220) in nearly quantitative yields (Equation (27)) <848771 >. On the other hand, tetrone (221) provides O-alkylated product (222) under the same conditions (Equation (28)) <66AP(299)44i >. C-Alkyl derivative (224) is obtained by treatment of the sodium salt of (223) with methyl iodide (Equation (29)) <78TL543>. 

The Pluronic and Tetronic surfactants (BASF) are examples of the polyoxyethylenated (PEO) polyoxypropylene (PPO) glycol type of nonionic surfactants. The Pluronic surfactants, are PEO-PPO-PEO triblock copolymers in which the PEO portion constitutes between 10 and 80% of the copolymer [92]. Pluronic F38 and F68 (both with HLB > 24) are typical examples of these surfactants used in emulsion polymerization formulations. The Tetronic surfactants are tetrafunctional block copolymers prepared from the addition of FPO and PEO to ethylene diamine, lypical examples of the Tetronic surfactants used in emulsion polymerization are Tetronic 707 and 908 (HLB > 24). The addition of these types of surfactants enhances freeze-thaw, shear and electrolyte stability, results in low foam formation and typically decreases the water sensitivity. 

Tetronic 904. See Poloxamine 904 Tetronic 908. See Poloxamine 908 Tetronic 1101. See Poloxamine 1101 Tetronic 1102. See Poloxamine 1102 Tetronic 1104. See Poloxamine 1104 Tetronic 1107. See Poloxamine 1107 Tetronic 1301. See Poloxamine 1301 Tetronic 1302. See Poloxamine 1302 Tetronic 1304. See Poloxamine 1304 Tetronic 1307. See Poloxamine 1307 Tetronic 1501. See Poloxamine 1501 Tetronic 1502. See Poloxamine 1502 Tetronic 1504. See Poloxamine 1504 Tetronic 1508. See Poloxamine 1508 Tetron Tetrasodium Pyrophosphate. See Tetrasodium pyrophosphate 1,3,5,7-Tetroxocane, 2,4,6,8-tetramethyl-. See Acetaldehyde, tetramer Tetrylammonium bromide. See Tetraethylammonium bromide Tetryl formate. See Isobutyl formate Teucrium chamaedrys Teucrium chamaedrys extract. See Germander (Teucrium chamaedrys) extract... 

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