Synthesis and characterization of novel conformers of (E)-2-(3-nitro-H-imidazo[1,2-a]pyridin-2-ylthio)-N'-benzylideneacetohydrazide derivatives.

Eighteen new N-acylhydrazones (9a-r) containing the imidazo[1,2-a]pyridine scaffold were synthesized through a seven steps reaction sequence, ending with a condensation of 2-(3-nitro-H-imidazo[1,2-a]pyridin-2-ylthio)acetohydrazide with various benzaldehyde derivatives (8a-r). All synthesized compounds were characterized by 1D NMR (1 H and 13 C NMR) and 2D NMR (NOESY) spectroscopic analyses and high-resolution mass spectrometry (HRMS). The analysis of 1 H NMR data performed at room temperature in deuterated dimethylsulfoxide (DMSO-d6 ) revealed the presence of (E)-2-(3-nitro-H-imidazo[1,2-a]pyridin-2-ylthio)-N'-benzylideneacetohydrazide (9a-r) as a mixture of two conformers, namely, syn-periplanar E (sp E) and anti-periplanar E (ap E). For all N-acylhydrazones that were synthesized, the sp E conformer was found to be the major form except in the case of hydrazone derived from o-hydroxybenzaldehyde.

Carbon-Phosphorus Bond Formation on Anilines Mediated by a Hypervalent Iodine Reagent.

Substituted anilines containing a sulfonyl group may be oxidized in situ in the presence of methanol and a hypervalent iodine reagent to form an active iminium species. Subsequent addition of phosphines or phosphites in the same pot produces meta-substituted anilines in good yields. This formal C-H bond functionalization is a direct and efficient means of selectively substituting the meta-position of anilines to produce aromatic phosphonium ions or phosphonates.

A Stereoselective Arylative-Cyclopropanation Process.

A new stereoselective arylative cyclopropanation process involving treatment of halogenated dienone systems in the presence of a Michael donor containing a nitro-aryl-sulfone has been developed. This transformation enables production of an arylated cyclopropane under mild conditions and occurs via a Michael-Smiles ring closure cascade process, reflecting the concepts of green chemistry and atom economy.

Crystal structure of 3-(2-hy-droxy-eth-yl)-2-methyl-sulfanyl-6-nitro-3H-benzimidazol-1-ium chloride monohydrate.

In the cation of the title hydrated molecular salt, C10H12N3O3S+·Cl-·H2O, the benzimidazolium ring system is almost planar (r.m.s. deviation = 0.006 Å) and the nitro group is inclined at an angle of 4.86 (9)° to this plane. In the crystal, C-H⋯O hydrogen bonds form centrosymmetric R22(20) dimers and these are further aggregated through N-H⋯O and O-H⋯Cl hydrogen bonds involving the water mol-ecules and chloride anions. Aromatic π-π stacking inter-actions are also found between two parallel benzene rings or the benzene and imidazolium rings, with centroid-centroid distances of 3.5246 (9) and 3.7756 (9) Å, respectively. Analysis of the bond lengths and comparison with related compounds show that the nitro substituent is not involved in conjugation with the adjacent π-system and hence has no effect on the charge distribution of the heterocyclic ring.

Use of the Nosyl Group as a Functional Protecting Group in Applications of a Michael/Smiles Tandem Process.

Concise preparations of elaborated polycyclic and heterocyclic systems present in natural products were obtained using the nosyl group as a functional protecting group not only to mask the reactivity of a sensitive moiety but also to provide a structure desired in the final target. The group is transferred to the substrate during deprotection through a novel extension of the Truce-Smiles rearrangement in tandem with a 1,4-addition. This strategy provides access to a ring system laden with valuable functionalities for subsequent manipulations and can serve as a versatile building block for the construction of more complex molecular architectures such as indoles in a manner compatible with the concepts of green chemistry and atom economy.