: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Readily accessible and shelf-stable 1,2,3-triazole and its analogues such as pyridotriazole, triazoloindole, benzotriazole, and thiadiazole exist in equilibrium with their ring-opened isomers, viz., diazo compounds. These ring-opened isomers could be trapped by various metal catalysts (e.g., Rh, Pd, Cu, Co, Ag, etc.) to generate the corresponding metal carbenoids with extrusion of nitrogen. As a consequence, these unique N-heterocycles facilitate access to a realm of N-containing complex structural motifs of biological importance through denitrogenative transformations such as transannulations, insertions, ylide formation, and rearrangements by trapping of the metal carbenoids with a diverse range of coupling partners (e.g., alkenes, alkynes, nitriles, carbo/heterocycles, X-H/C-X bonds, etc.). Hence, suitably substituted triazole derivatives have emerged as efficient surrogates of diazo compounds for the generation of reactive metal carbenoids during the past decades. In this comprehensive review, we aim to discuss in detail the remarkable advancement in their synthesis and synthetic applications.

1,2,3-Triazole and Its Analogues: New Surrogates for Diazo Compounds.

Transition Metal-Free, Free-Radical Sulfenylation of the α-C(sp3)−H Bond in Arylacetamides and Its Application Toward 2-Thiomethyl Benzoxazoles Synthesis

A straightforward domino approach to assemble benzoxazole-derived sulfonamides has been developed. The method is based on annulation-induced in situ generation of diazo compounds from readily available 2-(5-iodo-1,2,3-triazolyl)phenols, followed by metal-free denitrogenative transformation upon the action of 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) and amines. The protocol is operationally simple and features a broad substrate scope, furnishing a library of target compounds in generally good yields.

Domino Construction of Benzoxazole-Derived Sulfonamides via Metal-Free Denitrogenation of 5-Iodo-1,2,3-triazoles in the Presence of SO2 and Amines

The ability of [1,2,3]triazolobenzoxazinones to act as a source of "hidden" diazo group was discovered. These diazo precursors can be easily prepared by the intramolecular cyclization of 2-(5-iodo-1,2,3-triazolyl)benzoic acids. The Cu-catalyzed capture of the hidden diazo group allows for further functionalization through the denitrogenative pathway. The transformations proceed via the formation of either diazoimine or diazoamide intermediates. Novel routes to various anthranilamides as well as thiolated benzoxazinones were developed using the one-pot cyclization/diazo capture procedure.

Annulation-Triggered Denitrogenative Transformations of 2-(5-Iodo-1,2,3-triazolyl)benzoic Acids.

An efficient cascade approach to thiosubstituted benzoxazoles has been developed. The transformation starts with in situ generation of a diazo compound via annulation-triggered electrocyclic openin...

Uliana D. Moskalenko

Papers

Assembly of Thiosubstituted Benzoxazoles via Copper-Catalyzed Coupling of Thiols with 5-Iodotriazoles Serving as Diazo Surrogates.