Divergent and solvent dependent reactions of 4-ethoxycarbonyl-3-methyl-1-tert-butoxycarbonyl-1,2-diaza-1,3-diene with enamines

Palladium-catalysed alleneamination of γ,δ-unsaturated hydrazones with propargylic acetates: access to tetrahydropyridazines bearing allenes

A highly efficient palladium-catalysed alleneamination of γ,δ-unsaturated hydrazones with propargylic acetates has been developed. This novel method was used to synthesize tetrahydropyridazines bearing allene derivatives, and did so in moderate to good yields. This protocol features a simple catalytic system, broad substrate scope, easy scale-up, and versatile transformations.

Diastereoselective synthesis of functionalized tetrahydropyridazines containing indole scaffolds via an inverse-electron-demand aza-Diels–Alder reaction

A base-promoted and catalyst-free unprecedented inverse-electron-demand aza-Diels–Alder reaction between the in situ generated azoalkenes and 3-vinylindoles has been developed to afford tetrahydropyridazines containing indole scaffolds.

Regioselective construction of pyridazine and tetrahydrocinnoline derivatives via [4 + 2] cycloaddition–elimination with α-halogeno hydrazones and enaminones

Herein, we report the de novo construction of pyridazine scaffolds via a [4 + 2] cycloaddition–elimination reaction with α-halogeno hydrazones and enaminones.

B(C6F5)3-catalyzed metal-free hydrogenation of 3,6-diarylpyridazines

Metal-free hydrogenation of 3,6-diarylpyridaxines was realized for the first time to furnish 1,4,5,6-tetrahydropyridazine derivatives in 85–95% yields.

Synthesis of functionalized tetrahydropyridazines via catalyst-free self [4 + 2] cycloaddition of in situ generated 1,2-diaza-1,3-dienes

An efficient method for the synthesis of structurally diverse functionalized tetrahydropyridazines via self [4 + 2] cycloaddition of in situ generated 1,2-diaza-1,3-dienes was developed, which may play an important role in drug discovery.

[4 + 2] cycloaddition of in situ generated 1,2-diaza-1,3-dienes with simple olefins: facile approaches to tetrahydropyridazines

A catalyst-free [4 + 2] annulation process between in situ generated 1,2-diaza-1,3-butadienes and simple olefins has been developed. Under mild conditions, the reactions afforded 1,4,5,6-tetrahydropyridazines, which feature a wide range of bioactive compounds, with high yields (up to 99% yield).

Uncatalyzed one-pot synthesis of highly substituted pyridazines and pyrazoline-spirooxindoles via domino SN/condensation/aza-ene addition cyclization reaction sequence

A previously unknown class of highly substituted pyridazines and pyrazoline-spirooxinoles are easily prepared by an uncatalyzed one-pot three-component approach incorporating a domino SN/condensation/aza-ene addition cyclization reaction sequence. 1,1-Dihydrazino-2-nitroethylene (DHNE) which is generated in situ from the nucleophilic substitution (SN) reaction of hydrazine and 1,1-bis(methylthio)-2-nitroethylene (BMTNE), allowed to be condensed with active 1,2-dicarbonyl compounds followed by an intramolecular aza-ene addition cyclization to obtain the titled products depending on the type of 1,2-dicarbonyl. All reactions are easily performed and proceed with high efficiency under very simple and mild conditions without any catalyst and give good yields avoiding time-consuming, costly syntheses, and tedious workup and purification of products.