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

Abstract

Several derivatives of the novel 4-(4-methyl-5 H-pyrimido[4,5- b][1,4]thiazin-2-yl)morpholine and 4-methyl-2-(piperidin-1-yl)-5 H-pyrimido[4,5- b][1,4]thiazine ring systems have been synthesised through cyclocondensation of 5-amino-6-methylpyrimidine-4-thiols and the appropriate α-haloketone in glacial acetic acid under reflux.

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

“…Based on the mentioned facts and also in continuation of our previous studies in the synthesis of new heterocyclic compounds , the present study reports the synthesis of new derivatives of pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐ b ]quinoxaline through the one‐pot heterocyclization of the appropriate 5‐amino6‐methylpyrimidine‐4‐thiols and 2,3‐dichloroquinoxaline. N ‐alkylation of the synthesized compounds with several alkyl halides also gave the desired new derivatives of N ‐alkylated pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐ b ]quinoxalines ( 4a–h ).…”

“…Our previous published studies on the synthesis and using of 5‐amino6‐methylpyrimidine‐4‐thiols ( 1 ) in heterocyclization reactions prompted us to explore another aspects of treatment with the 2,3‐dichloroquinoxaline ( 2 ) thereby leading to the corresponding fused pyrimido[5′,4′:5,6] [1,4] thiazino[2,3‐ b ]quinoxaline ( 3a–d ) derivatives in the presence of K 2 CO 3 in dimethylformamide (DMF) under reflux. The heterocyclization occurred in one step and any intermediate was not isolated.…”

“…On the other hand, fused heterocyclic compounds containing pyrimidothiazine as central core in particular have been studied recently and found to possess wide biological properties, like antibacterial , antiparkinsonism , anti‐allergic , and 15‐Lipoxygenase inhibition . Commonly major methods for preparation of fused heterocyclic pyrimidothiazines have also been mentioned in the literature .…”