One-pot rapid and efficient synthesis of new spiro derivatives of 11H-indeno[1,2-b]quinoxalin-11-one, 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one and isatin-based 2-pyrazolines

Abstract

Some new spiro derivatives (5a-h, 9a-c and 13a-c) of 11H-indeno[1,2-b]quinoxalin-11-ones 1a-b and 6H-indeno[1,2-b]pyrido[3,2-e]pyrazin-6-one 6 and isatin 10 were synthesized by two different pathways. The chalcones 4a-h, 8a-c and 12a-c were prepared by the reaction of acetophenone and its four derivatives with 1a-b, 6 and 10 via base-catalyzed condensation followed by addition of acid. In the first procedure, the chalcones were isolated and reacted with hydrazine hydrate to give products. In the second procedure, the chalcones were in situ reacted with hydrazine hydrate without isolation to give spiro compounds in improved yields.

Recent advancement in the synthesis of diverse spiro-indeno[1,2-b]quinoxalines: a review

“…Previously, the same research group also reported the synthesis of spiro-indenoquinoxalinepyrazolines 6, separately by the reaction of chalcones 4 and hydrazine hydrate. 24 indenoquinoxaline 11 via four-component reaction of ninhydrin 1, benzene-1,2-diammine 2, tert-butyl isocyanide 10, and dialkylacetylenedicarboxylates 9 in dry CH 2 Cl 2 at room temperature in 8 h. In this process the intermediate indenoquinoxalinones 3 were generated in situ from the reaction of ninhydrin 1 and benzene-1,2-diamines 2 (Scheme 5).…”

Isatins As Privileged Molecules in Design and Synthesis of Spiro-Fused Cyclic Frameworks

“…An aldol-addition of acetophenones 312 to isatin 1 affords 3-hydroxy-3-phenacyloxindoles 313 which undergoes dehydration forming 3-phenacylidene-2-oxindoles 314 in quantitative yields that have been employed in the synthesis of spiro-dihydropyrimidinethione-oxindole 315 and spiro-pyrazoline-oxindoles 316 – 317 . , The reaction of compound 314 with phenylthiourea afforded the product 315 , whereas the reactions with phenylhydrazine and with hydrazine resulted in the formation of N -phenylpyrazoline 316 and pyrazoline 317 , respectively, spiro-fused to 2-oxindole (Scheme ).…”

Catalytic asymmetric [4 + 1] cycloaddition to synthesize chiral pyrazoline-spirooxindoles

“…Several strategies have been developed to prepare pyrazoline-spirooxindoles. One strategy is through amination/Michael reaction of chalcone-derived oxindoles and hydrazine hydrate, 4 but the asymmetric version of this method has not been attained yet (Scheme 1B-a). Another one is through [3 + 2] cycloaddition of alkenyloxindoles with α-diazocarbonyl compounds or nitrile imines as C 3 synthons.…”