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A three-component domino reaction for the synthesis of naphtho[2,3- b ][1,6]naphthyridine derivatives has been established. Such strategy exhibited excellent substrate scope including various enaminones and aldehydes that afforded a series of multifunctionalized naphtho[2,3- b ][1,6]naphthyridine derivatives with 70–86% yields. The advantages of bond-forming efficiency, accessibility of starting materials, and water as sole byproducts provide invaluable access to biological 1,6-naphthyridines. [ABSTRACT FROM AUTHOR]

A new three‐component domino reaction for the synthesis of 2‐amino‐6‐aryl‐5‐(phenylamino)‐3,7‐dihydro‐4H‐pyrrolo[2,3‐d]pyrimidin‐4‐one derivatives 4 using acetic acid as catalyst has been established. The reaction was performed in aqueous media using readily available and inexpensive 2,6‐diaminopyrimidin‐4(3H)‐one 1, 2,2‐dihydroxy‐1‐arylethan‐1‐one 2 and aniline 3 as substrates. The simple and efficient one‐pot three‐component approach, inexpensive catalyst, green reaction media, make the present methodology a good synthetic procedure. [ABSTRACT FROM AUTHOR]

A flexible and efficient three-component reaction has been established for the synthesis of bioactive 1,6-naphthyridine-2,5-diones by using low-cost and readily accessible aminopyridinones, aromatic aldehydes, and Meldrum's acid as starting materials. The main advantage of this synthetic method is that the yields of the resulting 1,6-naphthyridine-2,5-dione derivatives under ultrasound irradiation in water with acetic acid as catalyst are higher than those from the classical-heating method. The probable reaction mechanism indicates that the process involves a Knoevenagel condensation, Michael addition, and cyclization sequence. [ABSTRACT FROM AUTHOR]

An efficient approach for the synthesis of 2,6‐dimethyl‐1,3‐diarylpyrano[4,3‐b]pyrrol‐4(1H)‐one derivatives has been established. The reaction was performed in aqueous media using readily available and inexpensive 6‐methyl‐4‐(phenylamino)‐2H‐pyran‐2‐one and nitroolefin as substrates. The present methodology shows many attractive advantages, such as using water as green reaction media, inexpensive and environmentally friendly acetic acid as catalyst, easy work‐up procedure, and good to excellent yields. [ABSTRACT FROM AUTHOR]

A concise and efficient three-component domino strategy promoted by acetic acid has been established for the synthesis of novel spirocycloalkane fused pyrazolo[3,4- b pyridine-dicarbonitrile derivatives in 73–90% yields. The domino reaction is easy to perform by mixing 1 H -pyrazol-5-amines or isoxazol-5-amine, 2-arylidenemalononitriles, and cyclic ketones in the presence of acetic acid at 80 °C in 2–4 h. The present procedure shows attractive properties including inexpensive and easy starting materials, simple one-pot operation, large substrate scope, highly isolated yields, and easy purification process. This chemistry provides a promising synthetic strategy to construction of N -containing spirocycle skeleton with stereogenic centers. Image 1 • A reaction for synthesis of spirocycloalkane fused pyrazolo[3,4- b pyridines has been established. • The reaction can be finished within 2–4 h with water as sole byproduct. • This chemistry provides a strategy to construction of N -containing spirocycles with stereogenic center. [ABSTRACT FROM AUTHOR]

Direct and metal-free access to poly-substituted acenaphtho[1′,2':4,5]pyrrolo[3,2- c ]pyridin-11-one and its analogs was established through a simple one-pot reaction using enaminones and acenaphthylene-1,2-dione as basic substrates. The reaction allows the formation of C–N and C–C bonds accompanied by multiple bond cleavage in the presence of acetic acid. The approach features atomic economy, broad substrate scope, efficient and metal-free reaction conditions, inexpensive and readily available starting materials and easy operation, making the strategy highly attractive. Importantly, the new acenaphtho[1′,2':4,5]pyrrolo[3,2- c ]pyridin-11-ones with hydroxyl substituents could be further functionalized, affording access to molecular complexity and diversity. [Display omitted] • A [3 + 2] cyclization for the synthesis of acenaphtho[1′,2':4,5]pyrrolo[3,2- c ]pyridin-11-ones has been reported. • The typical advantages of this transformation is atomic economy. • The desired products with hydroxyl substituents could be further functionalized. [ABSTRACT FROM AUTHOR]

• A new domino approach for synthesis of pyrrolo[3,2- c pyridin-4-ones has been established. • The one-pot two-step four component strategy makes the reaction attractive. • The remarkable feature of the process is the formation of five C–N, C–C bonds initiated by sole acetic acid. A direct and metal-free access toward poly-substituted pyrrolo[3,2- c pyridin-4-one and its analogues have been established through a simple four-component, two-step reaction of 4-hydroxy-6-methyl-2 H -pyran-2-one, two amine molecules, and β -nitrostyrenes. The reaction allows the formation of five different C–N, C–C bonds by the multiple bond cleavage only using acetic acid as catalyst and solvent. The advantages of broad substrate scope, efficient and metal-free reaction conditions, inexpensive and readily available starting materials as well as simple one-pot two-step operation, make the strategy highly attractive. This transformation in acetic acid resulted in the rapid establishment of functional bioactive poly-substituted pyrrolo[3,2- c pyridin-4-one derivatives. [ABSTRACT FROM AUTHOR]