Studies in the synthesis and interconversion of isomeric triazolothienopyrimidines

Abstract

4‐Hydrazinothieno[2,3‐d]pyrimidines were cyclized with triethyl orthoformate and formic acid to give 1,2,4‐triazolo[4,3‐c]thieno[3,2‐e]pyrimidines and 1,2,4‐triazolo[2,3‐c]thieno[3,2‐e]pyrimidines depending on the reaction conditions employed.

Synthesis of Some New Condensed Pyrimidine Derivatives

“…After cooling the reaction mixture was poured into acidified cold water and the solid so-formed was collected by filtration and crystallized from ethanol to give an white crystals (Yield: 50%); mp 124 (3) (0.01 mol) in formamide (10 ml) was refluxed for 2 hrs. The reaction mixture after cooling was poured into cold water (40 ml) and the solid so-formed was collected by filtration and crystallized from (benzene-p.e (60-80 Ethyl(4-cyano-1,9-dioxo-1,9-dihydropyrimido[6,1-a] isoindol-3-yl)imidoformate (8): A mixture of compound (3) (0.01 mol), triethyl orthoformate (3 ml) and acetic anhydride (20 ml) was heated under reflux for 4 hrs. After cooling the reaction mixture was poured into water and the solid so-formed was collected by filtration and crystallized from ethanol as brown crystals, (Yield: 53%) ; m.p 130 ο C. To a solution of compound (8) (11): A solution of (0.01 mol) sodium nitrite in 10 ml of water was added to cold solution of compound (3) (0.01 mol) in acetic acid (30 ml) and concentrated hydrochloric acid (1.5 ml).…”

“…Also compound ( The condensation of compound (3) with triethyl orthoformate in refluxing acetic anhydride gave ethyl (4-cyano-1,9-dixo-1,9-dihydropyrimido [6,1-a] isoindol-3-yl) imidoformate (8). Treatment of compound (8) with nitrogen nucleophile resulted cyclization affording pyrimidopyrimidine derivatives (6).…”

An Efficient One-pot Two-component Protocol for Regio- and Chemoselective Synthesis of 5-Aryloyl-1,3,7,9-tetraalkyl-2,8-dithioxo-2,3,8,9-tetrahydro-1H-pyrano[2,3-d:6,5-d′]dipyrimidine-4,6(5H,7H)-diones

“…[10] Moreover, pyrane derivatives are well known for their antihistaminic activity. [11] Also, pyrimidines and their fused derivatives play an essential role in several biological processes of chemical and pharmacological importance.…”

Pyran and Pyridine as Building Blocks in Heterocyclic Synthesis

“…The reaction mixture was allowed to cool at room temperature then poured into water. The solid product was collected by filtration and crystallized from methanol/water to afford mercaptopyranopyrimidine (12).…”

“…Particularly, the 5-amino-9-chloro-2-(2-furyl)-1,2,4-triazolo [1,5-c] quinazoline (1) (Figure 1) was found to be a highly potent adenosine antagonist, 1 Also pyran and fused 4H-pyran derivatives have attracted a great deal of interest owing to their antimicrobial activity, 3,4,5 inhibition of influenza, virus sialidases, 6 mutagenic activity as antiviral, 7 antiproliferation agents, 8 sex pheromones activity, 9,10 antitumor 11 and anti-inflammatory agent. 12 Moreover, pyran derivatives are well known for their antihistaminic activity. 13 Also, pyrimidines and fused pyrimidines play an inertial role in several biological processes and have a considerable chemical and pharmacological importance.…”