2,3-Butanedione, reaction with

D-Erythrose undergoes self-aldolization in alkali solution, to form d- / co-L- /3 C6 TO-3-octulopyranose by combination of the 1,2-enediol and aldehyde forms. In weak alkali at 105°, syrupy D-erythrose yields d- /ycero-tetrulose, jS-D-a/tro-L-g/ycero-l-octulofuranose, and a-Ti-gluco-i -g/ycero-3-octulopyranose. At 300° in alkali, the major products from syrupy D-erythrose were 1-5% of butanedione (biacetyl) with smaller proportions of pyrocatechol, 33, 2,5-dimethyl-2,5-cyclohexadiene-l,4-dione (2,5-dimethylbenzoquinone), and 2,5-dimethyl-1,4-benzenediol (2,5-dimethylhydroquinone). It was assumed that D-erythrose is reduced to erythritol by a Cannizzaro type of reaction, followed by dehydration of erythritol to form biacetyl. However, very low proportions (<1%) of biacetyl are formed from erythritol compared with D-erythrose itself. Apparently, some other mechanism predominates in the formation of biacetyl. 

Tamariz et al. reported the synthesis of mukonine (11) based on a regioselective Diels-Alder reaction of N-phenyl-4,5-dimethylidene-2-oxazolidinone (634) with methyl propiolate (635). The diene 634 was prepared in moderate yield from the condensation reaction of 2,3-butanedione (632) with phenyl isocyanate (633). In an optimized reaction procedure using drastic basic hydrolytic conditions (KOH/ MeOH), followed by methylation with dimethyl sulfate, the adduct 636, was... 

The cycloaddition reactions of the unsymmetrical a-diazo-/3-diketone, 2-diazo-l-phenyl-l,3-butanedione 330, with diaryl imines 331 took place with high regioselectivity, affording exclusively the 6-methyl-5-phenyl-substituted 477-l,3-oxazin-4-ones 332 via the acetylphenylketene, generated by the thermal Wolff rearrangement of 330 (Equation 32) <2002HAC165>. 

Certain other 1,3-dicarbonyl chelates were brominated with difficulty or not at all. For example, the trifluoro- and hexafluoroacetylacetonates (VI, R = CF3, R = CH3, and R = R = CF3) were not brominated under a variety of vigorous conditions. However, in the case of the chromium chelates of 1-phenyl-1,3-butanedione and dibenzoylmethane (VI, R = C( Hr), R = CH5, and R = R = C(iHr)), reaction with N-bromosuccinimide (NBS) was successful. That the electron density at the central carbon of the chelate ring is an important factor in the success or failure of these electrophilic substitutions is evident from the fact that the bis-(ethylenediamine)-2,4-pentanedionocobalt(III) cation cannot be brominated even under vigorous conditions. 

There are also examples of the use of compounds that are converted into diketones under the conditions of the Pfitzinger reaction and then react with isatins. Thus, the diacid 56 (yield 58%) was obtained from 2-hydroxy-3-butanone and isatin 7 in the presence of potassium hydroxide in water [26], while the dicarboxylic acids 58 were synthesized from 3-chloro-2-butanone and isatins 57 [44], The initial chloro ketone is clearly saponified to 2-hydroxy-3-butanone under the reaction conditions. As in the reaction with isatin 7, the product is then oxidized to 2,3-butanedione, which reacts with two molecules of isatin. 

Glyoxal can be formed by oxidation of glycolaldehyde (e.g., in Scheme 2.5), but it can also be formed by autoxidation of unsaturated fats and by enzymic degradation of serine.60 2-Oxopropanal can be obtained by retroaldolisation of 1- and 3-deoxyglucosone or by hydrolysis of diacetylformoin (see Scheme 2.5). Butanedione can also be derived from diacetylformoin, but by reduction, dehydration, and hydrolysis (see Scheme 2.5). 2,3-Pentanedione can be formed from butanedione by aldol reaction with formaldehyde, dehydration, and reduction or by aldol condensation of hydroxyacetone and acetaldehyde, followed by dehydration. 

PET reaction of carbonyl compounds with olefins form either oxetanes (Paterno-Buchi reaction, Eq. 31) by direct coupling or a radical pair reaction leading to coupling product or reduction. The carbonyl-olefin radical pairs are formed by proton transfer within their radical ion pairs (Eq.32). Both these aspects of ketone-olefin photoreaction have been recently rationalized by Mattay et al. [167] from the photoreactions of 2,3-butanedione (208) with different olefins such as 209 and 210 as shown in Scheme 39. Photoprocesses of... 

When an isonitrosoketone reacts with an aldoxime, the product is an imidazole W-oxide.122 In a similar reaction Allan and Allan123 prepared 1-hydroxyimidazoles by the reaction of 2,3-butanedione-monoxime with aldehydes in aqueous ammonia. The overall reaction is undoubtedly the reaction of the isonitrosoketone with an aldimine by a mechanism similar to the following ... 

Synthesis of 2-[5-(l//-pyrrol-2-yl)-2-thienyl]-l//-pyrrole 1355, monomer for polyconjugated polymers, is based on the reaction of l,4-di(l//-pyrrol-2-yl)-l,4-butanedione 1354 with Lawesson s reagent (Equation 292) <1997CM2876>. Compound 1356 was prepared by Triton B-catalyzed condensation of 17/-pyrrole-2-carbaldehyde and the appropriate nitrile derivative (Equation 293). 

Arginine Phenylglyoxal Butanedione Phenylglyoxal can react with lysine Butanedione should be used in the dark to prevent reaction with tryptophans, histidines, and tyrosines... 

In Pina s work, 2,3-butanedione is trapped inside hemicarcerand 63 to give the corresponding hemicarceplex, and the reactions with several electron donors are investigated in order to elucidate the effect of the encapsulation on the rates of the electron transfer to the triplet excited state of the guest. The determination of phosphorescence quenching lifetimes of free and incarcerated 2,3-butanedione reveals that quenching for uncomplexed 2,3-butanedione occurs at the diffusion-controlled limits for any donor quencher (e.g., amines), whereas in the case of the encapsulated substrate the rate constants are lower (ranging between 3.5 x 10 and 4 X 10 s ) and display an approximately linear dependence upon the oxidation potential of the external quencher. In particular, rate constants decrease with the... 

The adduct (112) from phenyldichlorophosphine and stilbene undergoes a highly stereo selective oxidative addition reaction with o-aminophenol to form the cis-spirophosphorane (113) whose structure was confirmed (as the benzyl derivative) by X-ray crystallography and found to possess almost perfect tbp geometry. On the other hand, the reaction of (112) with catechol led stereoselectively to the trans configuration of the spirophosphorane (114)35. Cyclisation of (115) with PhPCl2 yields (116) which undergoes oxidative cycloaddition with 2,3-butanedione (117) to form the cis and trans forms of the - diphosphaspiro [4,4] -nonane (118).36... 

Bis(bromomethyl)quinoxaline (41), prepared by direct synthesis from o-phenylenediamine and l,4-dibromo-2,3-butanedione (BrCH2COCOCH2Br), can be similarly converted into the bispyridinium bromide 42, and this on treatment with p-nitroso-iV,N-dimethylaniline and sodium cyanide yields the biscyanoanil 44. Reaction with secondary amines such as diethylamine yields pyrroline derivatives (e.g., 43, see chapter XXXV). 

The reaction of l,4-dibromo-2,3-butanedione 78 with two moles of trimethyl phosphite produces the 2,3-diphosphate 79 via a double Perkow reaction.44... 

Ethyl acrylate also serves as a Michael acceptor and the reaction with l-phenyl-1,3-butanedione gives the corresponding addition product in high conversion (Scheme 5.3) [10]. 

The work also demonstrates that IMP in meat is a precursor for 2-methyl-3-furanthiol and mercaptoketones, although it does not seem to be as important in the formation of 2-furylmethanethiol. The roles of IMP and ribose as sources of these thiols have been discussed previously (12,19). The mechanism involves the Maillard reaction and could require the intermediate formation of 4-hydroxy-5-methyl-3(2H)-furanone and dicarbonyls, such as butanedione and pentanedione, which is then followed by their reaction with hydrogen sulfide or cysteine. The concentrations of IMP in meat vary considerably between different animals and different muscles, and are affected by production conditions both pre- and post-slaughter. The present results indicate that the amount of IMP in the meat at the time of cooking may be an important factor in determining the amount of meaty flavor. 

By reaction of benzil monohydrazone, 2,3-butanedione or 3,3 -dimethyl-l,2-butanedione monohydrazone with acetone in the presence of nickel(n), complexes [Ni(L122)]-(Ni(L124)] containing quadridentate open-chain ligands were obtained (Eq. 2.69). They consist of two residues of a monohydrazone a-dicarbonyl com-... 

Some methods for the synthesis of thiophene-substituted 1,4-diketones begin with the transformation of acetylthiophene. 2-Acetylthiophene 61 is reacted in a Mannich reaction with formaldehyde and dimethylamine to yield the corresponding Maimich base 62 in 70% yield. The Mannich base 62 is then subjected to a Stetter reaction [109] which results in l,4-di-(2 -thienyl)-l,4-butanedione 63 in 70% yield via the cyanhydrine of 2-thiophenecarbaldehyde [110]. Reaction of Mannich base 62 with the isomeric 3-thiophenecarbaldehyde under the same conditions results in l-(2 -thienyl)-4-(3 -thienyl)-l,4-butanedione 64 in lower (35%) yield [Eq. (27)] [110]. 

Butanedione is removed from the troposphere primarily by photolysis estimates of the lifetime for photodissociation within the lower troposphere with an overhead Sun are uncertain but estimated to be in the range from 0.8 h to 4 h (see figure IX-F-26 and table IX-M-1). The lifetime with respect to reaction with OH, for [OH] = 10 ... 

This regioselectivity is practically not influenced by the nature of subsituent R. 3,5-Disubstituted isoxazolines are the sole or main products in [3 + 2] cycloaddition reactions of nitrile oxides with various monosubstituted ethylenes such as allylbenzene (99), methyl acrylate (105), acrylonitrile (105, 168), vinyl acetate (168) and diethyl vinylphosphonate (169). This is also the case for phenyl vinyl selenide (170), though subsequent oxidation—elimination leads to 3-substituted isoxazoles in a one-pot, two-step transformation. 1,1-Disubstituted ethylenes such as 2-methylene-1 -phenyl-1,3-butanedione, 2-methylene-1,3-diphenyl- 1,3-propa-nedione, 2-methylene-3-oxo-3-phenylpropanoates (171), 2-methylene-1,3-dichlo-ropropane, 2-methylenepropane-l,3-diol (172) and l,l-bis(diethoxyphosphoryl) ethylene (173) give the corresponding 3-R-5,5-disubstituted 4,5-dihydrooxazoles. 

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