Mannich reaction of trifluoroacetaldehyde hydrazones: a useful entry to trifluoromethyl substituted heterocycles

Abstract

NH-aryl hydrazones derived from trifluoroacetaldehyde hemiacetal may be involved in efficient Mannich type reactions with formaldehydes and aromatic aldehydes. The resulting hydrazones are useful building blocks for the preparation of trifluoromethyl substituted heterocycles as shown by a straightforward preparation of 1,2-diazine derivatives under heating with β-ketoesters.

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

“…El Kaim and Jia reported a Mannich-type reaction of trifluoroacetaldehyde hydrazones with formaldehyde and aromatic alde- hydes to obtain valuable starting materials for the generation of other trifluoromethyl-substituted heterocycles. The study demonstrated that the electron-withdrawing property of the trifluoromethyl group is key to this coupling reaction [45] (Scheme 7).…”

Visible–Light–Induced Phosphorylation Reaction of α‐Diazoesters with H‐Phosphine Oxides to Construct (Z)‐Phosphinic Hydrazones

“…[2] Furthermore, functionalized hydrazones can also serve as valuable building blocks to construct various functional molecules in synthetic chemistry. [3] Consequently, some functionalized hydrazones such as acyl, [4] α-fluoroalkylated, [5] sulfonyl [6] and phosphinic hydrazones [7,8] have been thereby synthesized through various synthetic transformations. Among them, phosphinic hydrazones have received the special attention due to their interesting chemical and biological activities 8 and important synthetic applications.…”

Synthesis of Pyrazoles Utilizing the Ambiphilic Reactivity of Hydrazones

“…Hydrazones have emerged as an important class of compounds that serve as versatile intermediates in organic synthesis because of their multiple reactivities attributed to their unique structure . One of the most important features of hydrazones is the ambiphilic nature of the azomethine carbon (Scheme a). ,, Because of the intrinsic polarization of the CN bond similar to that of the carbonyl group, hydrazones have been employed as electrophiles in reactions with nucleophiles such as organometallic reagents .…”