Diketones cyclic, aromatization

Intramolecular coupling Some aromatic diketones have been stereoselectively cy-clized under various electrolysis conditions, which, together with the substrate structure, strongly influence the stereochemistry of the formed cyclic diol. Reductive cyclization of 1,8-diaroylnaphthalenes led to trans-diols, 2,2 -diaroylbiphenyls and a, )-diaroylalkanes yielded cis-diols with different stereoselectivities depending on substrate structure and electrolysis conditions (pH, cosolvent) (Fig. 57) [310-312]. 

Keywords Aromatic aldehydes, cyclic 1,3-diketones, p-keto compounds, anmumium acetate, ceric ammonium nitrate (CAN), ethanol, room temperature, one-pot multicomponent synthesis, Hantzsch condensation, polyhydroquinohnes... 

Polyfluorinated a-diketones react with 1,2-diainino compounds, such as ortlio-phenylenediamine, to give 2,3-substituted quinoxalmes [103] Furthermore, the carboxyl function of trifluoropyruvates offers an additional electrophilic center. Cyclic products are obtained with binucleophiles [13, 104] With aliphatic or aromatic 1,2-diamines, six-memhered heterocycles are formed Anilines and phenols undergo C-alkylation with trifluoropyruvates in the ortho position followed by ring closure to form y-lactams and y-lactones [11, 13, 52, 53, 54] (equation 23). 

Cyclic 1,2-diketones, 24 594 Cyclic acrolein acetals, 2 271 Cyclic amidine curing agents, 10 410 Cyclic amidines, 10 412 Cyclic (aromatic disulfide) oligomers, 23 712... 

Correlation of structure and reactivity in the oxidation of substituted aromatic anils by pyridinium fluorochromate (PFC) has been attempted using Grunwald-Winstein and Hammett equations. The stoichiometry between the substrate and oxidant is 1 2 in the oxidation of cyclic ketones by PFC to 1,2-diketones. PFC oxidation of secondary alcohols has been investigated. ... 

It was reported [59] that temperature in combination with the choice of catalyst is, indeed, the main factor in controlling the direction of this MCR. Under ambient and neutral conditions, the reaction between 5-amino-3-phenylpyrazole, cyclic diketones, and aromatic aldehydes yielded Biginelh-type dihydropyrimidines 54 (Scheme 24). Increase in the reaction temperature with simultaneous addition of triethylamine allowed the reaction to proceed along the thermodynamically controlled pathway with formation of dihydropyrazolopyridines 53. 

Indole derivatives such as dihydroindolone are scaffolds of potentially biological interest. Thus, the development of such functionalized skeletons has been approached by a MCR involving cyclic 1,3-diketones, cyclohexyl isocyanide, aromatic aldehydes, and ammonium acetate in the presence of catalytic amount of KHSO4 in refluxing acetonitrile (Scheme 30) [117]. hi this strategy, the imine derived from the Knoevenagel adduct reacts with cyclohexyl isocyanide to give the... 

A facile synthesis of substituted 2-hydroxy-3-dimethylaminopropenoates has been reported. These undergo addition with cyclic 1,3-diketones and (hetero)aromatic hydroxyl compounds to afford either 3-hydroxytetrahydro-277-Tbenzopyran-2-ones, benzo- and naphthopyran-2-ones, and azolo- and azinopyran-2-ones <1998T9799>. 

KETENE, feef-butylcyano-, 55, 32 37, 38 Ketene 1 1-dimethylpropylcyano-, 55, 38 7-KETOESTERS, 58, 79, 81, 82 7-KETOESTERS TO PREPARE CYCLIC DIKETONES, 58, 83 KETONE terf-butyl phenyl, 55, 122 Ketone, methyl ethyl- 55, 25 Ketone, methyl vinyl, 56, 36 KETONES, acetylenic, 55, 52 Ketones, alkylation of, 56, 52 KETONFS aromatic, aromatic hydrocarbons from 55, 7... 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

Nucleophilic additions of the acetonyl anion to 6-nitrotriazolopyrimidines (91) gave CT-adducts (227), whose acidification afforded the dihydro adduct 228 (93KGS807). Direct addition of cyclic /3-diketones such as dime-done and indanedione to 91 led to the adducts 229 and 230, respectively (93ZOR622). The reactivity of this class of compounds with respect to charged and uncharged nucleophiles is determined by their aromatic character and the deficit of electron density in the pyrimidine ring, and the di-... 

Quinones are not aromatic compounds but are conjugated cyclic diketones. Yet it is convenient to discuss their chemistry at this point because quinones and the related aromatic arenols are readily interconverted, and their chemistry is largely interdependent. 

For 3-aryl-5-aminopyrazoles 222 the direction of the multicomponent reaction with cyclic P-diketones and aromatic aldehydes is not so unequivocal. Quiroga et al. [190] found that during refluxing of these starting materials in ethanol, the reaction products were only derivatives of pyrazoloquinoline 227,... 

These disadvantages were avoided in the procedure proposed in [187]. The authors synthesized target pyrimido[4,5-Z>]quinolines in 90-98% yields and high purity (without any crystallization) by the multicomponent reaction of 6-ami-nouracil derivatives, aromatic aldehydes and cyclic 1,3-diketones under micro-wave irradiation in ethanol with Et3N as the catalyst. 

Ketones were found to be the major volatile components in boiled crayfish tail meats. A total of seven saturated ketones (C6 - Cll), one unsaturated ketone, one cyclic ketone, one aromatic ketone and two alkanediones were identified in the boiled crayfish tail meat. The two alkanediones, 2,3-butanedione and 2,3-pentanedione, gave an intense buttery and desirable aroma. Acetophenone imparted sweet rose floral odor. Four methyl ketones (C7 - Cll) and 2,3-pentanedione were identified in boiled crayfish hepatopancreas. Pour methyl ketones (C5 - C8) were identified in pasteurized crahmeat. These methyl ketones were usually associated with green, fruity aromas and gave more floral aromas as chain length increased. Several ketones (C4 - C8) also have been reported as volatile flavors of shrimp (13). The diketones might be important aroma components for crayfish tail meat and hepatopancreas products in providing desirable balance of the meaty and buttery notes. 

Fig (14) Olefin (107) has been converted to cyclic ether (114) by standard reactions. Its transformation to enone (115) is accomplished by annelation with methyl vinyl ketone and heating the resulting diketone with sodium hydride in dimethoxyethane. The ketoester (116) is subjected to Grignard reaction with methyllithium, aromatization and methylation to obtain the cyclic ether (117). Its transformation to phenolic ester (119) has been achieved by reduction, oxidation and esterification and deoxygenation. 

In 2008, Chebanov et al. reported an excellent example of condition base divergence by the MCR of 5-amino pyrazoles 135, cyclic 1,3 diketones 136 and aromatic aldehydes 137 (Scheme 12) [90]. 5-Amino pyrazoles 135 have at least... 

Chebanov and co-workers [130] described an efficient synthetic route for the synthesis of some novel derivatives of 5a-hydroxy-4,5,5a,6,7,8-hexahydropyra-zolo[4,3-c]quinolizin-9-ones 94 which is based on a multicomponent condensation of a 5-aminopyrazole with a cyclic 1,3-diketone and an aromatic aldehyde under microwave irradiation. The reaction runs via an unusual base-mediated ring-opening/recyclization of the cyclic 1,3-diketone moiety (Scheme 71)... 

The unsubstituted hydrazones derived from aromatic ketones (Table 1 entries 1, 5, 7,10, 11) a nd a Idehydes (entries 14 and 17), cyclic ketones (entries 19,24,25). including 3-oxo steroids (entries 28 and 29), as well as aliphatic ketones (entries 31, 34, 39) and aldehydes (entry 41) react under mild conditions yielding the expected gew-difluoro compounds. If the monohy-drazone of a diketone can be prepared, a,a-difluoro ketones are also available (entry 42). 

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