4.4- dimethyl-2,6-dioxo-1 - methyl

Purine, 1,6-dihydro-8,9-dimethyl-6-thioxo-synthesis, 5, 583 Purine, 2,6-dimethoxy-synthesis, 5, 596 Purine, 2,6-dimethoxy-7-methyl-rearrangement, 5, 558 Purine, 2,7-dimethyl-halogenation, 5, 547 Purine, 7,9-dimethyl-UV spectra, 5, 517 Purine, 8,8-dimethyl-synthesis, 5, 580 Purine, 6-dimethylamino-mass spectra, 5, 519 occurrence, 5, 600 Purine, 6-dimethylamino-9-benzyl-alkylation, 5, 531 Purine, 3,7-dimethyl-6,8-dioxo-methylation, 5, 534 Purine, 6,8-dioxo-alkylation, 5, 534... 

Heating either trimethyl 2-methyl-6-ethylidene-2,6-dihydro-l//-pyrido[l,2a]-pyrazine-7,8,9-tricarboxylate or tetramethyl 1,2-dimethyl-2,9a-dihydro-l//-pyrido-[l,2-a]pyrazine-6,7,8,9-tetracarboxylate in dilute HC1 gave dimethyl 2-methyl-7-propionyl-l,6-dioxo-2,6-dihydro-l//-pyrido[l,2-a]pyrazine-8,9-dicarboxylates (62JCS1510). 1,12-Dihydroxyper-hydrodibenzo[ac]pyrazine was prepared from l-(2-tetrahydrofuryl)-9-hydroxyperhydropyrido[l,2-a]pyrazine in AC2O saturated with HBr at 95-100°C (61BSF2135). 

Using an oxalic ester replaces a reactive hydrogen atom by an oxo ester (alkoxalyl) group.750 Thus diethyl 3-methyl-2-oxoglutarate is obtained in 70% yield from ethyl propionate and diethyl oxalate 751 and dimethyl dioxo-homonorcamphorate [methyl(3-methoxycarbonyl-2-oxocyclopentyl)glyoxalate] can be prepared in 90% yield from ethyl 2-oxocyclopentanecarboxylate and methyl oxalate 752... 

Trihydroxypteridine exists predominantly in the dioxo-mono-hydroxy form 191(R = H), its ultraviolet spectrum closely resembling those of both the 1- and the 3-methyl derivatives and that of l,3-dimethyl-7-methoxypteridine-2,4-dione (191, R = Me). These spectra are quite different from those of 8-methyl- (192, R = H) and l,3,8-trimethyl-pteridine-2,4,7-trione (192, R = Me), which are similar to each other and to those of other 8-substituted pteridine-2,4,7-triones. However, the ultraviolet spectrum of 2,4,7-trihydroxypteri-dine does, indeed, show that a small proportion of the trioxo form is present at equilibrium. A somewhat larger proportion of the 6-methyl derivative exists in the trioxo form, although structure 193 predominates. The trioxo form (194) of 2,4,7 trihydroxy-l,3,6-trimethyl-pteridine is the most important tautomer, but the corresponding 6-carboxylic acid exists entirely in the monohydroxy-dioxo form 195. 

Caffeine (128) and dimethyl sulfate in nitrobenzene give the fully methylated dioxo compound 129. In the same way that 2,4-dialk-oxypyrimidines give unstable quaternary salts which decompose to the N-alkyl oxo compounds even at room temperature, the action of... 

The 3-amino-8-oxo derivative of 1,2,4,5,7-pentaazanaphthalene (475) is known as well as various 3-substituted derivatives of the 6,8-dioxo compound. The 3-methylthio- and 3-ethylthio-6,8-dioxo derivatives and their 7-methyl and 5,7-dimethyl analogs were prepared by ring-closure. 3-Ethylthiopyrimido[4,5-e]-as-triazine-6,8-dione was 3-substituted with alkali 2N, 100°, > 30 min) or acid 2N, 100°, < 2 hr, 70% yield) and with ammonia, aniline, piperidine, or monoalkylamines (in pyridine, 115°, 4 hr, 75-85% yield). ... 

R = CH, methyl 3- 2,2-dimethyl-3,3-dioxo-i,3-oxathiun-4-yl)butanoate yield 62%... 

Dioxo-2,3-dimethyl-1,2,3,4-tetrahydro-phthalazin wird in Acetat-Puffer im we-sentlichen zuml-Oxo-2,3-dimethyl-l,2,3,4-tetrahydro-phthalazin (80% d.Th.) reduziert, in 4n Salzsaure wird dagegen unter Methylamin-Abspaltung 1 -Oxo-2-methyl-2,3-dihy-dro-isoindol (46% d.Th.) erhalten1 (vgl. a. S. 595f.) ... 

RN 59989-20-7 MF C.jH,oN40, CsH,>,NO MW 367.45 EINECS 262-012-4 CN 1,2,3,6-tetrahydro-l, 3-dimethyl-2,6-dioxo-7ff-purine-7-acetic acid compd. with 6-amino-2-methyl-2-heptaminol (1 1)... 

CiiHnNO 84080-68-2) see Cefixime 17,21-(l-butyl-l-methoxymcthylenedioxy)-3,20-dioxo-9-fluoro-lip-hydroxy-l(Sa-methyl-l,4-pregnadiene (C2gH3gF06 1062-64-2) see Dexamethasone valerate S-(crt-butyl 3-methyl 2,6-dimethyl-4-(3-nitrophenyl)-l,4-dihydropyridine-3,5-[Pg.2319]

V-[[l-[4-chloro-2-(2-chlorobenzoyl)phenyl]-3-[(dimethyl-amino)carbonyl]-l/f-l,2,4-triazol-5-yl]methyl]-l,3-dihy-dro-l,3-dioxo-2H-isoindole-2-acetamide (C29H22CI2NSO5 65699-00-5) see Rilmazafone... 

CioHi.jNOj 49831-65-4) see Calcium hopantenate 3P,5-dihydroxy-6p,17-dimethyl-5a-pregnan-20-one (C23H3JO1 95671-00-4) see Medrogestone lip,17-dihydroxy-3,20-dioxo-9a-fluoro-21-iodo-16P-methyl-l,4-pregnadiene... 

C2yH27N709S2 78968-24-8) see Temocillin [23 -(2ot,5ot,6a)]-6-[[l,3-dioxo-3-(phenylmethoxy)-2-(3-thienyl)propyl]amino]-6-methoxy-33-dimethyl-7-oxo-4-thid-l-azabicyc)o[3.2.0]beptane-2-carboxyIic acid phenyl-methyl ester... 

When dimethyl-2,2-dioxo-5-methyl-177,377-pyrrolo[l,2-r-][l,3]thiazole-6,7-dicarboxylate was heated under flash vacuum pyrolysis at 700°C/10 3mmHg, sulfur dioxide was eliminated and the vinylpyrrole 391 was obtained, which can be explained by allowed suprafacial [1,8]H shifts in the 871 1,7-dipolar system 390. Concerted sigmatropic shifts can only occur when the methyl groups adopt an inward (Z)-conformation (Scheme 57) <2002J(P1)1795, 2004TL3889, 2005JOC6629>. 

Cycloaddition of dimethyl l,2,4,5-tetrazine-3,6-dicarboxylate with EWG-substituted primary ketene N,0-acetals provides a tetrasubstituted pyridazine, methyl 4-amino-5,7-dioxo-6,7-dihydro-5/7-pyrrolo[3,4-4pyridazine-3-carboxylate <200681513>. 

Disubstituierte 5-Brom-6-methyl-2,4-dioxo-l, 2,3,4-tetrahydro-pyrimidine rcagieren mit aliphatischen Aminen in Dimethylformamid unter Ersatz des Brom-Atoms durch eine Amino-Gruppe4. Dagegen erfolgt bei Reaktion mit aromatischen Aminen allylische Substitution durch eine Arylamino-Gruppe, und man erhalt z.B. 6-Anilino-1,3-dimethyl-... 

The most important flavour compound in raw onions is thiopropanal-S-ox-ide, the lachrymatory factor [145,146]. Other important flavour compounds are 3,4-dimethyl-2,5-dioxo-2,5-dihydrothiophene and alkyl alkane thiosulfonates such as propyl methanethiosulfonate and propyl propanethiosulfonate with a distinct odour of freshly cut onions [35, 36, 147]. Various thiosulfinates that have a sharp and pungent odour may also contribute to the flavour of onions. These compounds, however, are rapidly decomposed to a mixture of alkyl and alkenyl monosulfides, disulfides and trisulfides (Scheme 7.3) of which dipropyl disulfide, methyl ( )-propenyl disulfide, propyl ( )-propenyl disulfide, dipropyl trisulfide and methyl propyl trisulfide are the most important contributors to the aroma of raw and cooked onions (Table 7.5, Fig. 7.6) [148-150]. Recently, 3-mercapto-2-methylpentan-l-ol was identified in raw and cooked onions eliciting intense meat broth, sweaty, onion and leek-like odours [142, 151]. 

DIETHYLPHOSPHONOMETHYL-2, 2-DIMETHYL-1.3-DI0XEN-4-0NE, 66, 194-196, 202 Diethyl phthalimidomethylphosphonate Phosphonic acid, (phthalimidomethyl)-, diethyl ester Phosphonic acid, [(1,3-dihydro-l, 3-dioxo-2H-isoindol-2-yl)-methyl]-, diethyl ester (33512-26-4), 65, 119 DIHYDR0JASM0NE, 65, 26... 

The order and mobility of a labeled flexible alkyl spacer in the linear thermotropic polymeric nematic liquid crystal poly(2,2 -dimethyl-4,4 -dioxyazoxybenzenedodecanedioyl-dj0) (poly[oxy(3-methyl-1,4-phenylene)azoxy 2-methyl-1,4-phenylene)oxy(1,12-dioxo-1,12-dodecanediyl-d2oll) is explored with deuterium NMR. The quadrupol splittings of the spacer methylene segments in the nematic melt of the polymer are reported as a function of the temperature and are contrasted with observations on model compounds solubilized in a nematic solvent. 

The dimethyl complex, MoC>2(Me)2(bipy), shows the expected cis dioxo structure345 with the methyl groups trans to each other and bent back from the oxo groups (C—Mo—C = 149°). The Mo—C distance is 2.19 A in the R = Me complex and 2.20 A in the R CH2Me3 complex. 

Dioxo-l,4,7,10-tetrahydro-l,10-phenanthroline (72) with dimethyl sulfate gives l,4-dihydro-7-methoxy-l-methyl-4-oxo- 1,10-phenanthroline (73) rather than a quaternary salt, steric hindrance presumably preventing alkylation of both nitrogens.203 A related alkylation has also been reported.295 1,2,3,4-Tetrahydro-1,10-phenanthrolines similarly form 1-alkyl derivatives rather than 10-alkyl quaternary salts with alkyl halides.38 The rate of methylation of 1,10-phenanthroline with methyl iodide in dimethyl sulfoxide has been studied,296 and the polaro-graphic reduction of 1 -methyl- 1,10-phenanthrolinium iodide was reported.286... 

Only one example of a derivative of this ring system has been reported. This compound, 2,6-dimethyl-3,4-dioxo-2,3,4,6,7,8-hexahydropyridazino[4,3-c]pyridazine 4-(p-bromo-phenylhydrazone) (149), was obtained in the reaction of the lactone (148) with methyl-hydrazine. A proposed mechanism for this unusual reaction is shown (80JHC617). 

Piperazine, l-diethylcarbamyl-4-methyl-metabolism, 1, 227 Piperazine, N,JV-dimethyl-epoxy resin curative, 1, 406 Piperazine, 2,5-dioxo-occurrence, 3, 187 Piperazine-2,5-dione polymers, 1, 298... 

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