Chemical behavior of 4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromene‐6‐carboxaldehyde towards carbon nucleophilic reagents

Abstract

The chemical behavior of 6‐formylkhellin (1) was investigated toward a variety of carbon nucleophiles. Treatment of aldehyde 1 with cyanoacetamide, N‐benzylcyanoacetamide produced pyridine‐3‐carboxamides 3 and 4. Treatment of carboxaldehyde 1 with malononitrile dimer and 1H‐benzimidazol‐2‐ylacetonitrile gave 1,6‐naphthyridine 5 and pyrido[1,2‐a]benzimidazole 6, respectively. Some novel pyrazolo[3,4‐b]pyridine 7, pyrido[2,3‐d]pyrimidines 8 and 9 were synthesized from the ring opening ring closure reactions of carboxaldehyde 1 with certain heterocyclic enamines. In addition, reaction of carboxaldehyde 1 with certain cyclic enols produced a variety of products. Treatment of carboxaldehyde 1 with 1,3‐cyclohexanediones gave xanthene‐1,8‐diones 19 and 20. Reaction of carboxaldehyde 1 with 5‐methyl‐2,4‐dihydro‐3H‐pyrazol‐3‐one proceeds in 1:2 M ratio producing pyrazolo [4′,3′:5,6]pyrano[2,3‐c]pyrazole derivative 22. Carboxaldehyde 1 reacted with certain heterocyclic compounds containing active methylene groups to give the corresponding condensation products 22‐27. The synthesized compounds were screened in vitro for their antimicrobial activity and showed high to moderate activities against the tested microorganisms.

A “Neat” Synthesis of Substituted 2-Hydroxy-pyrido[1,2-a]pyrimidin-4-ones

“…They were first synthesized in 1924, 13 but have only been recognized as an important scaffold more recently. [14][15][16][17][18] Specific examples of approved active pharmaceutical ingredients based on a PPD pharmacophore include permirolast, 19 an anti-allergen medication, and risdiplam, 20 a treatment for spinal muscular atrophy (Figure 1). Additional studies indicate PPDs have potential as compounds for cancer treatment, 21 and diabetes.…”