Functionalized pyrano[2,3-c]pyrazoles were synthesized from 2,4-dihydro-3H-pyrazol-3-ones, active... more Functionalized pyrano[2,3-c]pyrazoles were synthesized from 2,4-dihydro-3H-pyrazol-3-ones, active carbonyl compounds and tert-BuOH in the presence of trifluoroacetic acid at 65 °C. These reactions are proceeded by acid catalyzed generation of isobutylene from tert-BuOH for LUMOdiene-controlled inverse [4 + 2] cycloaddition reaction with in situ-generated vinylidenepyrazolones.
An ultrasound-promoted green protocol to access a new series of spirocyclopropanes from indeno[1,... more 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 the iodine-catalyzed reaction of acetophenones as well as of 2-methylquinoline with pyridine in the presence of a base, is described. These transformations proceed 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 analysis. The most important feature of this reaction is the fact it forms three stereogenic centers, one of which is quaternary, with excellent selectivity.
A convenient Michael addition/cyclization sequence of alkyl isocyanide–acetylenic ester zwitterio... more 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.
An efficient transition-metal-free approach toward C–H bond activation by using molecular $$\hbox... more An efficient transition-metal-free approach toward C–H bond activation by using molecular $$\hbox {I}_{2}$$I2-mediated $${ sp}^{3}$$sp3 C–H bond functionalization for the synthesis of indolizine derivatives via 1,3-dipolar cycloaddition reaction of nitrogen ylides with ynones is described.Graphical Abstract
Functionalized pyrano[2,3-c]pyrazoles were synthesized from 2,4-dihydro-3H-pyrazol-3-ones, active... more Functionalized pyrano[2,3-c]pyrazoles were synthesized from 2,4-dihydro-3H-pyrazol-3-ones, active carbonyl compounds and tert-BuOH in the presence of trifluoroacetic acid at 65 °C. These reactions are proceeded by acid catalyzed generation of isobutylene from tert-BuOH for LUMOdiene-controlled inverse [4 + 2] cycloaddition reaction with in situ-generated vinylidenepyrazolones.
An ultrasound-promoted green protocol to access a new series of spirocyclopropanes from indeno[1,... more 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 the iodine-catalyzed reaction of acetophenones as well as of 2-methylquinoline with pyridine in the presence of a base, is described. These transformations proceed 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 analysis. The most important feature of this reaction is the fact it forms three stereogenic centers, one of which is quaternary, with excellent selectivity.
A convenient Michael addition/cyclization sequence of alkyl isocyanide–acetylenic ester zwitterio... more 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.
An efficient transition-metal-free approach toward C–H bond activation by using molecular $$\hbox... more An efficient transition-metal-free approach toward C–H bond activation by using molecular $$\hbox {I}_{2}$$I2-mediated $${ sp}^{3}$$sp3 C–H bond functionalization for the synthesis of indolizine derivatives via 1,3-dipolar cycloaddition reaction of nitrogen ylides with ynones is described.Graphical Abstract
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