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1.2.3.4- Tetrazines, fused

Triazines, Tetrazines and Fused Ring Polyaza Systems... [Pg.268]

Two oxadisilole-fused benzo[c]furans illustrated below were prepared making use of Warrener s tetrazine protocol <06JOC3512>. Their reactivities, photophysical, redox and thermal properties were all assessed. As shown below, an isocorannulenofuran was also synthesized, again by employing Warrener s route, from readily accessible bromocorannulene <060L5909>. [Pg.199]

Triazines, tetrazines and fused ring polyaza systems... [Pg.414]

Pyrimido[3, 2 4,5]thieno[3,2-rijpyrimidinoncs reacted with hydrazonoyl halides in dioxane and triethylamine to give the corresponding tetracyclic fused tetrazines <06JHC935>. [Pg.428]

Another convenient entry to fused cyclobutene-1,2-diesters was via site selective modification of the norbomene rt-bond in Smith s fe-alkene 49, e.g. treatment with 3,6-di(2 -pyridyl)-s-tetrazine 51 followed by DDQ oxidation afforded the cyclobutene-derivative 53 <97AA119>, while direct coupling with 3,5-f> (trifluoromethyl)-l,3,4-oxadiazo]e 54 furnished the tas(cyclobutene-l,2-diester) 55 (Scheme 6) <97SL196>. [Pg.29]

Similarly, [4 + 2]-cycloadditions were used to prepare the pyridazine moiety in fused tetraheterocyclic azepine 155 syntheses. In this reaction, the 1,2,4,5-tetrazines 154 function both as the 47t-components and the oxidizing agents thereby requiring four equivalents of tetrazine for optimal yield. . [Pg.276]

These authors found that the tetrazinylhydrazone derivative 46 when reacted with pyrrolidinoenamine 47 in methanol yields the cyclopenta-fused derivative of the title ring system 48 in 94% yield. A similar transformation was carried out successfully by using morpholine-enamine in somewhat poorer yield. When the transformation was tried in acetonitrile as a solvent, a totally different reaction was observed a regular Diels-Alder reaction between the tetrazine ring and the enamine double bond (of inverse electron demand) took place to yield pyridazines. [Pg.903]

Arylidene-33-diethyl-3,4,6,7-tetrahydro-2//-thiazolo[3,2-/j][l, 4 ]-tetrazin-6-ones 53 have been synthesized in a single step by the condensation of tetrahydro-l, 4 -tetrazin-3-thione 52 with ethyl chloioacetate and aldehydes in the presence of pyridine and piperidine. Condensation of 53 with hydrazine afforded fused derivatives 54 <98IJC(B)819>. [Pg.302]

The conformational equilibria of the l,2,4,5-tetraalkylhexahydro-l,2,4,5-tetrazines (474) and related fused-ring systems are the most complicated of the systems treated in this review. The elucidation of these equilibria and... [Pg.162]

Deprotonation from the azonium group leaves a lone pair of electrons on the nitrogen atom, and a neutral aza substituent. The known parent monocyclic azines (see Scheme la) include all the possible diazines and triazines, but only one tetrazine, the 1,2,4,5-isomer. Some 1,2,3,5-tetrazines have been reported, but only when heavily substituted or fused. Some aromatic bicyclic 1,2,3,4-tetrazines have been prepared (see Section 4.4.8.2.3) as well as reduced 1,2,3,4-tetrazines (see CHEC 2.21). No pentazines are known. All attempts to prepare hexazine also failed though several claims about fixation of the latter in a matrix have appeared. [Pg.15]

Pyrimidines are expected to be much less reactive in cycloadditions of this type than triazines and tetrazines. Normally, the presence of electron-withdrawing substituents on the pyrimidine ring is essential. The best results are obtained with a nitro group in position 5. Reaction of 5-nitropyrimidine with various enamines affords fused nitropyridines (82TL3965 89T2693) (Scheme 59). The mechanism (89T2693) is in agreement with the usual expectations. [Pg.343]

This procedure is also efficient for the synthesis of other fused tetrazoles, such as ethyl l,5-dihydro-5-oxo-7-phcnyl-8-(phenylsulfonyl)tetrazolo[ 1,5- pyridine-6-carboxy late <2000J(P1)3686>. At the same time, the unexpected azido-tetrazolo tautomerization and reversible tetrazolo transformation of 3,6-diazido-l,2,4,5-tetrazine are remarkable compared to all other polyazido heteroaromatic high-nitrogen C-N compounds <2005JA12537>. [Pg.374]


See other pages where 1.2.3.4- Tetrazines, fused is mentioned: [Pg.200]    [Pg.1]    [Pg.126]    [Pg.202]    [Pg.250]    [Pg.104]    [Pg.304]    [Pg.666]    [Pg.901]    [Pg.280]    [Pg.88]    [Pg.1]    [Pg.539]   
See also in sourсe #XX -- [ Pg.53 , Pg.180 ]




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