Domino Reaction of Arylglyoxals with Pyrazol-5-amines: Selective Access to Pyrazolo-Fused 1,7-Naphthyridines, 1,3-Diazocanes, and Pyrroles

Abstract

New multicomponent domino reactions of arylglyoxals with pyrazol-5-amines have been established, providing selective access to unprecedented pyrazolo-fused 1,7-naphthyridines, 1,3-diazocanes, and pyrroles (up to 52 examples). The unreported dipyrazolo-fused 1,7-naphthyridines were regioselectively synthesized through a special double [3 + 2 + 1] heteroannulation accompanied by direct C–C formation between two electrophilic sites of arylglyoxals. The unusual [3 + 3 + 1 + 1] cyclization resulted in 20 examples of novel dipyrazolo-fused 1,3-diazocanes, whereas pyrrolo[2,3-c]pyrazoles were obtained in good yields by varying arylglyoxals 1 and pyrazol-5-amines 2 in the ratio 1:2. Mechanisms of formation of these three new types of heterocycles are also proposed.

Pyrazolo-fused 4-azafluorenones as key reagents for the synthesis of fluorescent dicyanovinylidene-substituted derivatives

“…Numerous approaches for the synthesis of PP 11,12 and their fused derivatives have been reported, 13,14 those reactions involved the interaction of 1,3-bis-electrophilic compounds with N-substituted 5-aminopyrazoles. [11][12][13][14] Moreover, multicomponent reactions (MCRs) are used in the synthesis of these compounds by the formation in situ of the bis-electrophilic intermediate. This approach has been widely used in diversity-oriented synthesis (DOS) of biologically active heterocyclic compounds.…”

Multicomponent Reactions of Arylglyoxal, 4‐Hydroxycoumarin, and Cyclic 1,3‐C,N‐Binucleophiles: Binucleophile‐Directed Synthesis of Fused Five‐ and Six‐Membered N‐Heterocycles

“…Under acidic conditions, reaction of arylglyoxal, aminopyrazole, and aromatic amines provide pyrrolopyridine and fused indoles (Scheme , Equation 2) . However, arylglyoxal and aminopyrazole derivatives in the presence of the acidic catalyst para ‐toluenesulfonic acid ( p TsA) in N , N ‐dimethylformamide (DMF) provide diverse interesting products dependent upon the type of substituents and the ratio of the substrates (Scheme , Equation 3) . Similarly, the four‐component reaction of arylglyoxal, aminopyrazole, aromatic amine, and dimedone/4‐hydroxy‐6‐methyl‐2‐pyrone provide either tetracyclic or tricyclic fused heterocycles (Scheme , Equation 4) .…”

Site‐Selective Convergent Synthesis of Spiroacridines through a Cascade Reaction of Enaminones with Acenaphthoquinone: An Efficient Construction of Multiple C−C and C–Heteroatom Bonds

“…Enaminonesare readily available synthons in organics ynthesis and have been widely used in the preparation of av ariety of heterocyclic and fused heterocyclic compounds. [17] Many of the fused heterocyclest hat are formed from enaminones have promising biological activity. [18] The enaminone structure (Scheme 1) containse lectron-donating N-aryl and electronwithdrawing carbonyl groups.The three reactive sites of enaminonesi nclude the b-carbon atom, the nitrogen atom of the secondary amine, and the carbonyl carbon atom.…”