Iodine mediated cascade oxidative functionalization, cyclisation and annulation reactions

Molecular iodine has a huge application in the field of electrophilic cyclisation reactions, oxidation, oxidative cyclisation, multi-component reactions, ring opening, cyclisation, rearrangement, oxidative cross coupling, oxidative annulation, C-H functionalization reactions, synthesis of heterocycles and its derivatives. In this mini review I discuss the utilization of iodine mediated cascade reactions for oxidative annulation, functionalization and cyclisation of various organic compounds.

Dearomative [4 + 2] annulations between 3-nitroindoles and enals through oxidative N-heterocyclic carbene catalysis

A novel intermolecular dearomative [4 + 2] annulation of 3-nitroindoles and enals under oxidative N-heterocyclic carbene catalysis has been developed. This protocol was also suitable for the oxidative cyclisation of 2-nitrobenzothiophenes with enals.

Ru-catalysed oxidative cyclisation of 1,5-dienes: an unprecedented role for the co-oxidant

The Ru-mediated oxidative cyclisation of 1,5-dienes to THF-diols proceeds with the intermediacy of NaIO4-complexed Ru(vi) species and offers new insights into the Ru-catalysed functionalizations of alkenes and 1,5-dienes.

TFA/TBHP-promoted oxidative cyclisation for the construction of tetracyclic quinazolinones and rutaecarpine

An efficient TFA/TBHP-promoted oxidative cyclisation of readily available isatins with 1,2,3,4-tetrahydroisoquinolines has been firstly developed. The potential utility of this strategy was demonstrated by one-step synthesis of a natural alkaloid Rutaecarpin.

Unveiling the active isomer of cycloalanopine, a cyclic opine from Lactobacillus rhamnosus LS8, through synthesis and analog production

Stereochemistry of the antimicrobial isomer of a cyclic opine was determined by synthesis using oxidative cyclisation of a bis-hydrazide.

Synthesis of New 3,7,9-Trisubstituted Pyrazolo[4,3-e][1,2,4]Triazolo[4,3-c] Pyrimidines Acyclo C-Nucleosides via Oxidative Cyclisation

Condensation of 4-hydrazino-1,3-diphenylpyrazolo[3,4-d]-pyrimidine with the aldohexoses, namely, D-glucose, D-galactose, D-mannose and the aldopentoses, D-arabinose, D-xylose and D-ribose, by heating in an aqueous ethanol in the presence of a catalytic amount of HCl, gave the respective aldehydo-sugar hydrazones. Oxidative cyclisation of such hydrazones by stirring with iron(III) chloride in ethanol at room temperature afforded the expected acyclo C-nucleosides 3-substituted-7,9-diphenylpyrazolo[4,3-e][1,2,4]triazolo[4,3-c]-pyrimidines. The structures of the cyclised sugar hydrazones were confirmed by their elemental analyses and spectral data.