Suzuki-aza-Wittig, Suzuki-condensation and aza-Wittig-electrocyclic ring-closure tandem reactions for synthesis of fused nitrogen-containing ring systems

Abstract

We describe tandem combinations of Suzuki-aza-Wittig, Suzuki-condensation and aza-Wittigelectrocyclic ring closure reactions for the synthesis of new pyridazino [4,5-c]

Tandem mass spectrometric study of annelation isomers of the novel thieno[3′,2′:4,5]pyrido[2,3-d]pyridazine ring system

“…On the other hand if the benzyl group is missing (compounds 8 1,5 and 9 1,5 ) the fragmentation pattern of the 2 molecules are similar (m/z=155, m/z=153, m/z=141, m/z=128), but the intensities of fragment ions are completely different and the two isomers can also be distinguished. The peak at m/z=128 is the most intense peak in the case of compound 8, while m/z=153 is the base peak in the tandem mass spectrum in the case of compound 9.…”

“…[5][6][7] In this paper the application of Suzuki -condensation ring closure tandem reaction is described for the synthesis of a novel thieno[3′,2′:4,5]pyrido [2,3-d]pyridazine ring system. Among starting material of our previous works also 5-azido-4-bromopyridazin-3(2H)-ones derivatives have been applied for synthesis route azide→iminophosphorane→Suzuki-aza-Wittig tandem reaction.…”

Electrospray ionization–tandem mass spectrometric study of fused nitrogen‐containing ring systems

“…The chlorine-substituent in 8 and 11 had no effect on the fragmentation. Pyrimido-quionoline (13) and pyrimido-cinnolines (14 and 15) tended to give fragments originated predominantly from the pyrimidine ring.…”

“…11,12 The studied compounds were synthesized by Suzukicondensation ring closure tandem reactions as we described in our previous studies. [13][14][15][16] In continuation of our work on the mass fragmentation mechanisms of the thieno[3 0 ,2 0 :4,5]pyrido [2,3-d]pyridazine ring system, 17 a detailed study on fused N-heterocycles was performed to understand the fragmentation behaviour of these compounds. This paper reports a study on the fragmentation mechanisms under ESI/MS conditions of pyridazino-indoles (1-6), pyridazino-quinolines (7)(8)(9)(10)(11)(12), a pyrimido-quinoline derivative (13) and pyrimido-cinnolines (14)(15).…”

“…Pyrimido-quinoline13 showed fragmentation only on the pyrimidine ring during the MS experiments. m/z = 276 fragment was detected after the ejection of a H 3 CNC=O.…”