An efficient transition-metal-free approach toward C-H bond activation by using molecular [Formula: see text]-mediated [Formula: see text] C-H bond functionalization for the synthesis of indolizine derivatives via 1,3-dipolar cycloaddition reaction of nitrogen ylides with ynones is described.

A novel synthesis of spirocyclopropane‐1,4′‐pyrazolin‐5′‐one derivatives via iodine‐mediated C(sp3)–H activation is described. Thus, a diastereoselective synthesis of spirocyclopropane‐linked pyrazolones from 4‐arylidene‐3‐methyl‐1‐phenylpyrazolin‐5‐ones and azomethine ylides, generated in situ from iodine‐catalyzed reaction of 2‐methylquinoline or acetophenones with pyridine in the presence of base, has been developed. These transformations proceeded via a cyclopropanation reaction followed by anti‐elimination of pyridine. Unequivocal evidence for the structures of spirocycles rac‐anti‐5 a and rac‐anti‐12 a were obtained from single‐crystal X‐ray analyses. These methods offer several advantages, such as being inexpensive, moderate to high yield, high atom economy, and ease of product isolation, which make them attractive processes for the synthesis of spirocyclopropane‐linked pyrazolones. The spirans reported in this work may deserve further attention not only from a synthetic but also from a pharmacological point of view.

A convenient Michael addition/cyclization sequence of alkyl isocyanide–acetylenic ester zwitterionic adducts with various pyrazolone derivatives, leading to the formation of dialkyl 6-(alkylamino)-1-methyl-4-oxo-3-phenyl-9-aryl-2,3-diazaspiro[4.4]nona-1,6,8-triene-7,8-dicarboxylates in moderate to good yields, is described. The structure of the target compounds was confirmed by an X-ray diffraction study.

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An ultrasound-promoted green protocol to access a new series of spirocyclopropanes from indeno[1,2-b]quinoxaline derivatives and azomethine ylides, generated in situ from iodine-catalyzed reaction of acetophenones as well as 2-methylquinoline with pyridine in the presence of a base, is described. These transformations proceeded via a spirocyclopropanation reaction followed by elimination of pyridine. Clear evidence for the structure of a spirocyclopropane-linked indenoquinoxaline derivative was obtained from single-crystal X-ray analyses. The most important feature of this reaction is the fact it forms three stereogenic centers, one of which is quaternary with excellent selectivity.