Polyfunctional fused heterocyclic compounds via indene‐1,3‐diones

Microwave Assisted Synthesis and Biological Evaluation of 1, 2, 4-Triazolo[1, 5-a]pyrimidines

“…Furthermore, certain lithium 1,3-diketonates have proven to be better synthons than the corresponding diketones 15 . Previous mechanistic conclusions have been confirmed by isolating stable intermediate 5-amino-1, 2, 4-triazole derivatives such as enamine (6) (Scheme 2) on reacting 5-amino-1, 2, 4-triazoles with 3-ketovinyl ethers 16 , 3-ketoenamines 17 , 3-ketoaldehydes 18 , enamine-2-carboxylic esters 19 or ethoxymethylene malonates 20 . …”

Microwave assisted synthesis of annelated benzosuberone as new penta-heterocyclic ring systems

“…14,15 To explore the utility of this, we investigated the reaction between 6-[(dimethylamino)methylene]-6,7,8,9-tetrahydro-5H-benzo [7]annulen-5-one (1) and 6-amino-2-thioxo-2,3-dihydropyrimidin-4(1H)-one (2) in glacial acetic acid [under reflux for 5 hours or pressurized microwave irradiation for 5 min.]. This reaction produced tetra-heterocyclic ring system, namely, 3-thioxo-2,3,4,7,8,9-hexahydro-1H-benzo [6',7']cyclohepta [1',2':4,5] pyrido [2,3-d]pyrimidin-1-one (3) or its isomeric structure (4) (Scheme 1).…”

Dimethylformamide dimethyl acetal as a building block in heterocyclic synthesis

“…Treatment of compound (239 0 a) with indene-1,3(2H)-dione in boiling ethanol leads to the formation of acyclic structure (240), which is converted into cyclic compound (241) when boiled in glacial acetic acid [155]. Reaction of (239b) with ethyl cyanoacetate gave (242) as a mixture of isomers, which on thermal cyclization gave the 4-hydroxyquinoline (243).…”

“…Enamine (147) was also coupled with benzenediazonium chloride to afford 2-oxo-4-[2-oxo-1-(phenylhydrazono)-ethyl]-2H-chromene-3-carbonitrile (150). Treatment of (147) with cyanothioacetamide, 3-aminocrotononitrile, urea, glycine, and 2-aminopyridine affords fused heterocyclic compounds (151)(152)(153)(154)(155), respectively, as shown in Scheme 23 [104][105][106].…”

“…Also condensation of compounds (246a-e), which were prepared by reaction of (245a-e) with DMFDMA and indene-1,3-dione in boiling acetic acid leads to the formation of compounds (247a-e) as shown in Scheme 35 [155].…”