6,7,8,9-Tetrahydrodipyrimido[4,5-b][4?,5?-e][1,4]thiazine derivatives. Synthesis and structure

Journal of Heterocyclic Chem

2018

As a continuation of our search for new heterocyclic compounds, the synthesis of pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐b]quinoxaline ring system is described. A series of new derivatives of this heterocyclic system (3a–d) have been synthesized through the one‐pot heterocyclization of the appropriate 5‐amino6‐methylpyrimidine‐4‐thiols and 2,3‐dichloroquinoxaline in the presence of K2CO3 in dimethylformamide under reflux. N‐alkylation of the synthesized compounds with alkyl halides in KOH/dimethylformamide also gave the desired new derivatives of N‐alkylated pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐b]quinoxalines (4a–h). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.

Section: Introductionmentioning

confidence: 99%

Synthesis of New Pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐b]quinoxaline Derivatives in One Step

Journal of Heterocyclic Chem

2018

“…From the chemical point of view, a few methods for the synthesis of pyrimidothiazines have also been reported in the literature .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of New Derivatives of 4‐(4,7,7‐Trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine

Journal of Heterocyclic Chem

Bakavoli

Shiri

2015

Cyclocondensation of 5‐amino‐6‐methyl‐2‐morpholinopyrimidine‐4‐thiol (1) and 2‐bromo‐5,5‐dimethylcyclohexane‐1,3‐dione (2) under mild reaction condition afforded 4,7,7‐trimethyl‐2‐morpholino‐7,8‐dihydro‐5H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐9(6H)‐one (3). The 1H and 13C NMR data of compound (3) are demonstrated that this compound exists primarily in the enamino ketone form. Reaction of compound (3) with phosphorous oxychloride gave 4‐(9‐chloro‐4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine (4). Nucleophilic substitution of chlorine atom of compound (4) with typical secondary amines in DMF and K2CO3 furnished the new substituted derivatives of 4‐(4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine (5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.

“…20,21 Commonly employed methods for the synthesis of fused-ring pyrimidothiazines have also been reported in the literature. 21,[22][23][24][25][26][27][28] In view of the aforementioned facts and also in continuation of our research program on the synthesis of new heterocyclic compounds, 21,22,29,30 we now report the synthesis of new derivatives of 4-(4-methyl-5H-pyrimido [4,5-b][1,4]thiazin-2-yl)morpholine and 4-methyl-2-(piperidin-1-yl)-5H-pyrimido [4,5-b][1,4]thiazine. All the synthesised products were characterised and confirmed by their spectroscopic and microanalytical data.…”

mentioning

confidence: 99%

Synthesis of new derivatives of 4-(4-methyl-5H-pyrimido[4,5-b][1,4]thiazin-2-yl)morpholine and 4-methyl-2-(piperidin-1-yl)-5H-pyrimido[4,5-b][1,4]thiazine

Journal of Chemical Research

2017