Catalytic 1,1-diazidation of alkenes

Compared to well-developed catalytic 1,2-diazidation of alkenes to produce vicinal diazides, the corresponding catalytic 1,1-diazidation of alkenes to yield geminal diazides has not been realized. Here we report an efficient approach for catalytic 1,1-diazidation of alkenes by redox-active selenium catalysis. Under mild conditions, electron-rich aryl alkenes with Z or E or Z/E mixed configuration can undergo migratory 1,1-diazidation to give a series of functionalized monoalkyl or dialkyl geminal diazides that are difficult to access by other methods. The method is also effective for the construction of polydiazides. The formed diazides are relatively safe by TGA-DSC analysis and impact sensitivity tests, and can be easily converted into various valuable molecules. In addition, interesting reactivity that geminal diazides give valuable molecules via the geminal diazidomethyl moiety as a formal leaving group in the presence of Lewis acid is disclosed. Mechanistic studies revealed that a selenenylation-deselenenylation followed by 1,2-aryl migration process is involved in the reactions, which provides a basis for the design of new reactions.

Reactions with Geminal Diazides: Long Known, Full of Surprises, and New Opportunities

Geminal diazides are uncommon yet powerful tools in organic synthesis. The chemistry of this class of functional compounds is characterized by quite unusual reactivities, including fragmentations and degradations, along with known reactions of organic azides. This Short Review highlights the major reactivities of various structural units having geminal diazido moieties, and provides an overview on the synthetic opportunities of such compounds.

1 Introduction

2 Preparation of Geminal Diazides

3 Reactivities of Geminal Diazides

3.1 α,α-Diazido Carbonyls

3.2 1,3-Diketones

3.3 Diazidated β-Ketoesters

3.4 Diazidated Malonates

3.5 Diazidated Malonamides

3.6 Miscellaneous Geminal Diazides

4 Conclusion

Taming the reactivity of alkyl azides by intramolecular hydrogen bonding: site-selective conjugation of unhindered diazides

The intramolecular hydrogen bonding in the α-azido secondary acetamides (α-AzSAs) enabled site-selective integration onto the diazide modular hubs even without steric hindrance.

Luminescent terpyridine appended geminal bisazide and bistriazoles: multinuclear Pt(II) complexes and AIPE-based DNA detection with the naked eye

We report square planar Pt(ii) complexes as luminescent biosensors for DNA detection in solution. The sensing is attributed to the aggregation induced bright red photoluminescence (AIPE) of the complexes in the presence of DNA that can be seen with the naked eye using only a 360 nm light source. Terpyridine appended luminescent geminal bistriazoles (L1-L4, from geminal bisazide A through azide-alkyne 'click' cycloaddition) with versatile chelating sites were explored for metal coordination and reaction with Pt(dmso)2Cl2 yielding tetranuclear and dinuclear complexes of Pt(ii) with different N∩N ligand environments. Thermally stable gem-bisazide and bistriazoles are hardly reported in the literature and this is the first report of terpyridine appended geminal bisazide and bistriazoles.

Rubazonic Acids and Their Synthesis

Rubazonic acids are a class of dyes that are long-known, but studies on their syntheses and uses are rare. We now describe an experimentally simple and highly practical one-pot procedure for their synthesis starting from easily accessible 1H-pyrazol-5(4H)-ones. This protocol provides direct access to a broad range of the desired rubazonic acid derivatives through oxidative diazidation combined with a reductive work-up, without the need to isolate the potentially hazardous diazido compounds generated en route the target compounds. We also show how more challenging variants of rubazonic acid are efficiently prepared using an alternative two-step procedure and controlled hydrogenation conditions.

The CuAAC: Principles, Homogeneous and Heterogeneous Catalysts, and Novel Developments and Applications

The copper-catalyzed azide/alkyne cycloaddition reaction (CuAAC) has emerged as the most useful "click" chemistry. Polymer science has profited enormously from CuAAC by its simplicity, ease, scope, applicability and efficiency. Basic principles of the CuAAC are reviewed with a focus on homogeneous and heterogeneous catalysts, ligands, anchimeric assistance, and basic chemical principles. Recent developments of ligand design and acceleration are discussed.

A Synthetic Route Toward Tetrazoles: The Thermolysis of Geminal Diazides

A new synthetic route toward the tetrazole core is described, which is based on a general fragmentation pattern that was found in a range of compounds featuring geminal diazido units. Through a simple two-step procedure, the synthesis of structurally diverse target compounds containing a tetrazole, such as tetrazoloquinoxalinones, benzoylaryltetrazoles, tetrazolotriazinones, and tetrazoloazepinones, was easily accomplished, starting from broadly accessible substrates (i.e., oxindoles, diarylethanones, pyrazolones, and phenanthrols). The initial oxidative diazidation reaction with iodine and sodium azide under mild conditions is followed by the thermal fragmentation under microwave irradiation, leading to the tetrazole products. Noteworthy, an experimental solution is presented in which the potentially hazardous diazide intermediates are not isolated and the concentration of crude reaction mixtures containing diazides is not required to achieve the tetrazoles in good yields.