Diazophosphonates: Effective Surrogates for Diazoalkanes in Pyrazole Synthesis

Addition of diazoalkanes to alkyne(pentacarbonyl) /chromium and /tungsten */ formation of 3H-pyrazole complexes

Photolysis of [M(CO)6] (M /Cr, W) in CH2Cl2 at /78 8C generates [(CO)5M(CH2Cl2)]. Subsequent sequential reaction of [(CO)5M(CH2Cl2)] with terminal alkynes, HC /CR (R /COOMe, Ph, p -Tol), and diazoalkanes, R (R)CN2 (R 1 /Me, Et, Ph; R2 /Me, Et) affords 3H -pyrazole complexes, [(CO)5M / N N C(R) C(H) C /(R)(R)]. These complexes are derived from addition of diazoalkanes to alkyne complex intermedi...

Cu-catalysed pyrazole synthesis in continuous flow†

Synthesis of Chromone-Related Pyrazole Compounds.

Chromones, six-membered oxygen heterocycles, and pyrazoles, five-membered two-adjacent-nitrogen-containing heterocycles, represent two important classes of biologically active compounds. Certain derivatives of these scaffolds play an important role in medicinal chemistry and have been extensively used as versatile building blocks in organic synthesis. In this context, we will discuss the most r...

Synthesis of New Pyrazole Derivatives Using Vinamidinium Salts

Novel pyrazole derivatives 2-7 are synthesized by the reaction of 2-substituted 1,3-bis(dimethylamino)-trimethinium salts with phenyl hydrazine in acetonitrile as the solvent. This method has some advantages of high yields (78-85%), simplicity of the process and easy of control. The ultraviolet spectral behavior of the synthesized compounds is examined in CDCl3 and their structures were charact...

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

The amide moiety of peptides can be replaced for example by a triazole moiety, which is considered to be bioisosteric. Therefore, the carbonyl moiety of an amino acid has to be replaced by an alkyne in order to provide a precursor of such peptidomimetics. As most amino acids have a chiral center at Cα, such amide bond surrogates need a chiral moiety. Here the asymmetric synthesis of a set of 24...