Synthesis and Chemistry of Unusual Bicyclic Endoperoxides Containing the Pyridazine Ring

Abstract

Inverse-Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with unsaturated bicyclic endoperoxides gave the bicyclic endoperoxides containing the pyridazine ring. The NEt(3) and CoTPP (TPP = tetraphenylporphyrin) catalyzed reaction of endoperoxide 8 resulted in the formation of hydroxy ketone 11 and cis-diol 9. Cleavage of the peroxide linkage in 8 with thiourea provided cis-diol 9. Oxidation of hydroxy ketone 11 and cis-diol 9 led to the phthalazine-5,8-dione 10. Furthermore, the various transformations of the other endoperoxides 19, 20, 22, 23, and 30 resulted in the formation of pyridazine derivatives.

Synthesis of Some Novel Norbornene‐Fused Pyridazines as Potent Inhibitors of Carbonic Anhydrase and Acetylcholinesterase

“…The most widely utilized synthetic method for substituted pyridazines with structural diversity is the inverse electron demand Diels-Alder reaction between the electronpoor tetrazines with electron-rich dienophile [45][46][47][48][49][50][51]. The general strategy for the preparation of a series of differently substituted pyridazines is outlined in Scheme 1.…”

Rearrangements of organic peroxides and related processes

“…Therefore, this is an efficient approach to the synthesis of syn -1,2:3,4-diepoxides from 1,3-dienes under mild conditions. Table 30 summarizes the results of the cobalt(II) tetraphenylporpyrin-catalyzed rearrangement of endoperoxides 576 [ 509 ], 578 [ 510 ], 580 [ 511 ], 582 [ 512 ], 584 [ 353 ], 586 [ 513 ], 588 [ 514 ], 590 , 592 [ 515 ], 594 [ 516 ], 596 [ 517 ], and 598 [ 518 ] which afforded products structurally similar to the diepoxides prepared by thermal rearrangement of endoperoxides ( Table 25 ). All rearrangements were stereospecific and yielded only the syn -diepoxides.…”

Synthesis of Pyridazine and Pyrrole Analogues of 2‐Aminotetralin as Potential Dopaminergics

“…Refluxing the mixture in benzene afforded the benzyl carbamate 7 in 76% yield through the Curtius rearrangement . Inverse electron demand Diels–Alder additions (iEDDA) between 1,2,4,5‐tetrazines and olefins are very well known for the preparation of pyridazines . These reactions result in the formation of bicyclic intermediates via nitrogen elimination readily and subsequent rearranging, yielding dihydropyridazines, which may be further oxidized to pyridazines.…”