Sydnones 3- -4-methyl

Sydnone, 3-methyl-conductance, 6, 371 dielectric constants, 6, 368 dipole moments, 6, 368 Sydnone, 3-methyl-4-phenyl-nitration, 6, 372... 

Kinetic parameters k, often also and AS, occasionally AV ) for formation and dissociation of several pentacyanoferrate(II) complexes [Fe(CN)5L]" have been established. Ligands L include several S- and A-donor heterocycles,4-methyl- and 4-amino-pyridines, a series of alkylamines, 3- and 4-hydroxy- and 3- and 4-methoxy-pyridines, several amino acids, nicotinamide, " 4-pyridine aldoxime, 3-Me and 3-Ph sydnones, several bis-pyridine ligands,neutral, protonated, and methylated 4,4 -bipyridyl, 1,2-bis(4-pyridyl)ethane and traTO-l,2-bis0-pyridyl)ethene, pyrazine- 4,4 -bipyridyl- and bis(4-pyridyl)ethyne-pentaammine-cobalt(III), edta-ruthenium(III), and pentaammineruthenium-(II)and-(III) complexes of... 

Metallation reactions at C-4 of sydnones have been reviewed <95H(4l)i525>. Typical conditions for 3-arylsydnones involve reaction of the sydnone with butyllithium at — 50°C <86BCJ483> methyl-magnesium bromide has also been used as the base <92MI 403-02>. These reactions are invariably used as a means of effecting electrophilic substitution at C-4 as described in Section 4.03.7. 

Dumitrascu and co-workers (52) transformed 4-halosydnones into 5-halopyr-azoles by cycloaddition with DMAD and methyl propiolate followed by retro-Diels-Alder loss of CO2. Turnbull and co-workers (194) reported that the cycloadditions of 3-phenylsydnone with DMAD and diethyl acetylenedicarboxylate to form pyrazoles can be achieved in supercritical carbon dioxide. Nan ya et al. (195) studied this sydnone in its reaction with 2-methylbenzoquinone to afford the expected isomeric indazole-4,7-diones. Interestingly, Sasaki et al. (196) found that 3-phenylsydnone effects the conversion of l,4-dihydronaphthalene-l,4-imines to isoindoles, presumably by consecutive loss of carbon dioxide and A-phenylpyrazole from the primary cycloadduct. Ranganathan et al. (197-199) studied dipolar cycloadditions with the sydnone 298 derived from A-nitrosoproline (Scheme 10.43). Both acetylenic and olefinic dipolarophiles react with 298. In... 

Nan ya et al. (93,94) also reported the reaction of sydnones with Al-methyl- and N-phenylmaleimides. Gribble and Hirth (206) extended the work of Weintraub (207) on the tandem dipolar cycloaddition of sydnones with 1,5-cyclooctadiene to afford diazatetracycloundecanes 305. 

Ethyl-3-(2-methyl-propyl)-sydnon Eine Losung von 1,98 g (10 mmol) 4-Ethyl-3-(2-mcthyl-propyl)-N-nitroso-sydnon-imin in 7 ml Dimethylformamid wird auf dem kochenden Wasserbad bis zur vollstandigen Entfarbung ( 10 min) erwarmt. Das Losungsmittel wird i. Vak. entfernt und das Rohprodukt aus Diethylether umkristallisicrt Ausbeute 1,67 g (98%) Schmp. 45 46". 

Die Photolyse von 3,4-Diphenyl-sydnon liefert dagegen zu 25% 2,4,5-Triphenyt-l,2,3-tri-azol4 1 4S. Ein ahnliehes Ergebnis wird fiir 3-(4-Methyl-phenyl)-4-phenyl- und 3,4-Bis-[4-methyl-phenyl]-sydnon erhalten. 

Aus 2-(Cyclohexyl-nitroso-amino)-propansaure-nitril erhalt man mit Essigsaureanhydrid 3-Cyclohexyl-4-methyl-sydnon-acetylimin [83% Schmp. 92-94° (Zers.) (Essigsaure-ethyle-ster)]. 

The polarographic reductions of cephaloridine, cephalothin, and cephalosporin C each yield one wave that is both pH and concentration dependent [126]. The reduction of these compounds and a related derivative, 3-(5-methyl-1,3,4-thiadiazol-2-ylthiomethyl)-7-[2-(3-sydnone)acetamido]-3-cephem-4-carboxylic acid-sodium salt [I], have been described [127]. The reduction of I yields two waves. The first is believed to be the two-electron reductive elimination of the... 

Mesoionic compounds have been known for many years and have been extensively utilized as substrates in 1,3-dipolar cycloadditions.158-160 Of the known mesoionic heterocycles, munchnones and sydnones have generated the most interest in recent years. These heterocyclic dipoles contain a mesoionic aromatic system i.e. 206) which can only be depicted with polar resonance structures.158 Although sydnones were extensively investigated after their initial discoveiy in 1935,160 their 1,3-dipolar character was not recognized until the azomethine imine system was spotted in the middle structure of (206). C-Methyl-N-phenylsydnone (206) combines with ethyl phenylpropiolate to give the tetrasub-... 

The 13C spectra of several sydnones and sydnonimines have been determined (74JCS(P2)875). In 3-methylsydnone the IV-methyl carbon resonance is at 39.8 p.p.m. and the ring carbons 4 and 5 resonate at 96.8 and 169.2 p.p.m., respectively. These data and those for other sydnones have been correlated with ring structure. 

Methyl-2-oxazolidinone A-methyl-2-pyrrolidinone 3-Methyl sydnone Pyridine... 

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