4- Methyl-1,2,4-triazoline-3,5-dione

Fig.8A,B Derivatization of Type I pheromones A Z7-12 OAc with dimethyl disulfide (DMDS) and mass spectra of the DMDS adduct B E5,Z7-12 OAc with 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) and mass spectra of the MTAD adduct...

A case of a thermally induced phase change involving ring inversion was recently described by Kaftory (31). He found that a crystal of the exo isomer of the adduct, 7a, of ll-cyano-l,6-methano[10]annulene with 4-methyl-1,2,4-triazoline-3,5-dione is transformed to the endo isomer 7b on heating to 175°C. The process involves nucleation and growth of the product phase, but maintains... 

Methyl-1,2,4-triazoline-3,5-dione (2) [1, 697, before Methyltriphenylphosphonium bromide]. Mol. wt. 112.09, red crystals, m.p. 98-98.5°. Preparation1 by oxidation of 4-methylurazole (1) with dinitrogen tetroxide. 

Phenyl l,2,4-triazoline-3,5-dione, is an extremely reactive dienophile and enophile that is at least 1000 times more reactive in the Diels-Alder reaction with 2-chlorobutadiene than tetracyanoethylene (TONE) and 2000 times more reactive than maleic anhydride. 4-Methyl-1,2,4-triazoline-3,5-dione, 2, is at least 30,000 times more reactive towards cyclohexene than its open chain analog, ethylazodicarboxylate. The many reactions of these powerful electron-acceptor molecules are generally quite rapid, being complete within a matter of seconds within the range of 0 C to room temperature. 

Cl2H12BrNO, 6-(p-Bromobenzoyl)-6-azabicyclo[3.1.0]hexane, 33B, 128 Cl2H13N3O2, ([4.2.1]Propella-2,4-diene)-(4-methyl-1,2,4-triazoline-3,5-dione), 46B, 291... 

Methyl urazol 302 was oxidized into A-methyl triazoline-3,5-dione with tert-buiy hypochlorite. Without isolation, it was then reacted with ( )-penta-2,4-diene-l-ol giving adduct ( )-303 as a racemic mixture. On treatment of ( )-303 with a lipase (R/Novozym 435) in vinyl acetate, 38% of ester (5)-304 (86% ee) and 29% of alcohol (/ )-303 (59% ee) were isolated. Epoxidation of (5 )-304... 

In order to smdy the effect of perturbation arising from spiro-conjugation on the chemical reactivities, in particular the facial selectivities, sterically unbiased dienes (96 and 97) based on fluorenes in spiro geometry have been synthesized [165]. These dienes react as Diels-Alder dienes with several dienophiles (maleic anhydride (MA), A-phenylmaleimide (PMI), A-phenyl-l,3,5-triazoUne-2,4-dione (PTD) and iV-methyl-l,3,5-triazoline-2,4-dione (MTD)). 

Methyl-3-(tetramethylcyc opropylidene)propene (176), obtained by isomerization of allene 175 with potassium ferr-butoxide, added to 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD, 177) at room temperature to give the Diels-Alder adduct 178 in 46% yield (Scheme 26) [43]. 

The reaction of 4-methyl-l,2,4-triazoline-3,5-dione 428 with tetracyclopropylethylene gives 5,5,6,6-tetracyclopropyl-3-methyl-5,6-dihydro-oxazolo[3,2-A][l,2,4]triazolium-2-olate 140 (unreported yield) (Equation 89) <2004JA700>. 

Coupling of excess (Z)-l,2-dichloroethene (217) with propargyl alcohol first led to the enyne 218, which, when subjected to a second Pd-catalyzed coupling step with trimethylsilylacetylene, provided the mixed diacetylene 219. With all carbon atoms assembled, the allene function was generated by first producing the (unprotected) hydrazine derivative 220, which on treatment with either diethyl azodicarboxylate (DEAD) or 4-methyl-l,2,4-triazoline-3,5-dione (MTAD) under anaerobic conditions at 0 °C yielded the hydrocarbon 27. According to mechanistic studies, the latter process leads first to a mixture of ( )- and (Z)-diazenes. Sigmatropic elimination of... 

Treatment of l-benzoyl-6-methyl-l,6-dihydro-l,2,4-triazine-3,5-dione (126) with bases led to the 5-phenyl-1,2,4-triazolin-3-one (127) (03JA386). 

The structure of 91, a new bisaikylidenesilirane (sila[3]radialene) system, was confirmed by X-ray structure analysis (Figure 3c). Because of the high kinetic stability of 91 due to steric protection, aldehydes such as benzaldehyde as well as ketones did not react. However, [2 + 4] cycloaddition chemistry of 91 with 4-methyl-l,2,4-triazoline-3,5-dione resulted in the formation of a new ring-fused silirene (97) (equation 26). 

A 1,4-dipolar cycloaddition between tetrahydropyrido[l,2-a]pyrimidi-none 114 (R = Me) and 4-methyl-l, 2,4-triazoline-3,5-dione 666gave stable adduct 667 in acetonitrile or in acetic acid at room temperature for 1 hour (Scheme 44) (85CB4567). When ethyl cyanoformate was used as dienophile in boiling toluene for 20 hours, ethyl 3-methyl-4-oxo-6,7,8,9-tetrahydro-4//-pyrido[ 1,2-a]pyrimidine-2-carboxylate 669 was obtained (86CB1445). Pyrido[l,2-a]pyrimidine-2-carboxylate 669 was formed from the initial adduct 668 by elimination of phenyl isocyanate. Reaction of tetrahydropyr-ido[l,2-a]pyrimidinone 114 (R = Me) with l-(diethylamino)-l-propyne in... 

The aziridinofullerenes and azafulleroids obtained by Mattay et al. were subjected to further reactions to yield fullerene adducts of the second generation. As a model compound 4-methyl-l,2,4-triazoline-3,5-dione (NMTAD) 187, which is one of the most reactive dienophiles for Diels-Alder reactions, was selected. Sheridan et al. studied the photoinduced [4 + 2] cycloadditions of NMTAD to arenes [295], With alkenes, however, NMTAD reacts in photoinduced cycloadditions in a [2 + 2] fashion under formation of diazetidines [296], Both the sulfonyl-azafulleroids (185) and aziridinofullerene (186) were irradiated at 420 nm to give both the same [2 + 2] cycloadduct 186 (Scheme 71) [291], This indicates that at a certain stage rearrangements must be involved. 

Oxidation of hydrazines to diazines. Propargylic hydrazines are oxidized rapidly and efficiently in CH3OH at 0° by 4-methyl-l,2,4-triazoline-3,5-dione (MTAD) or diethyl azodicarboxylate (DEAD) with evolution of nitrogen to provide the corresponding allenes in 50-70% yield. The reaction occurs with high stereospecificity, and can be used to obtain optically active allenes (equation I).1... 

H and 13C KIEs were determined for the ene reaction of 4-phenyl-l,2,4-triazoline-2,5-dione (PTAD) with 2-methyl-2-butene 44 or 2-methyl-l-pentene 45 (Scheme 7).91 Authors assumed that although in the reaction of 2-methyl-l-pentene two products are formed, reactions should proceed via very similar transition states in the first mechanistic step. 

Products F and G were in turn substrates for subsequent pairing reactions to obtain multicyclic compounds J, N, K, O, and H. Finally, products B, J, and H, which all comprise a diene functionality could be further converted by a subsequent Diels-Alder (DA) reaction with 4-methyl-l,2,4-triazolin-3,5-dione to obtain the highly complex products I, M, and L. This example shows that by applying the build/couple/pair strategy a collection of 15 highly diverse (and complex) scaffolds can be obtained in only three to five steps. ... 

Another synthesis of side-chain-hydroxylated cholesta-5,7-dien-3/S-ol derivatives uses the aldehyde (386), prepared by ozonolysis of the adduct of ergosteryl acetate with 4-phenyl-l,2,4-triazoline-3,5-dione. An aldol condensation between the aldehyde (386) and the pre-formed enolate of 3-methyl-3-tetrahydro-pyranyloxybutan-2-one (387) led to the enone (388), after acidic work-up. Reduc-... 

CYCLOADDITIONS f-Butyicyanoketene. a-Chloro-N-cyclohexylpropanaldoxime. Chlorosulfonyl isocyanate. Dichloroke-tene. Dimethyl acetylenedicarboxylate. Diphenyl ketene, 2-Methoxyallyl bromide. 2-Methoxy-6-methyl-l,4,3,5-oxathiadia-zine 4,4-dioxide. Oxygen, singlet. 4-Phen-yl-l,2,4-triazoline-3,5-dione. Silver fluoro-borate. Trimethylsilyldiazomethane. 

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