β-Alkoxyvinyl trifluoromethyl ketones as efficient precursors for the one-pot synthesis of bis-(4,5-dihydro-1H-pyrazol-1-yl)methanones and 1H-pyrazolyl-1-carbohydrazides

Abstract

The one-pot and regioselective synthesis of a novel series of 3-aryl(heteroaryl)-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazolyl-1-carbohydrazides and bis-(3-aryl-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl)methanones from the cyclocondensation reactions of 4-alkoxy-4-aryl(heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones, where aryl substituents are H, Me, Ph, 4-OMePh, 4-ClPh, 4-BrPh, 4,4'-biphenyl and heteroaryl are 2-thienyl and 2-furyl, with carbohydrazide is reported.

Unsaturated polyfluoroalkyl ketones in the synthesis of nitrogen-bearing heterocycles

“…In almost all cases the required heterocycles were isolated in moderate to high yields aer long reuxing of initial reagents in alcohol. [60][61][62][63][64][65][66][67][68][69] As it was observed for hydrazines, the use of ionic liquids 70 and microwave activation in the presence 71 or absence 72,73 of solvent shortened reaction time as well. The selectivity of reactions with hydrazides under these conditions was not affected at all.…”

Easy and regioselective access to dimethyl acetal-protected heterocycles and their efficient allylation reactions mediated by allylaluminum reagent

“…Since the trifluoromethyl group shows changes in physico-chemical properties such as polarity, lipophilicity and polarizability, chemical behavior, 1 and pharmacological activity of the molecules to which it is connected, 2,3 this substituent has become increasingly popular in heterocyclic compounds synthesized for biological application. [4][5][6] Over the last twenty years our research group (NUQUIMHE) has reported on the synthetic potential of β-alkoxyvinyl trihalomethyl ketones for obtaining of new trihalomethylated heterocycles, [7][8][9][10][11][12] as well as other molecules that provide great possibilities for chemical heterocycles containing a stable dimethyl acetal-protected aldehyde function as a substituent for further chemical transformations has not yet been described. So, the one-step synthesis of heterocycles that have a protected aldehyde function (such as an acetal moiety) deserves considerable attention.…”