A general strategy for the synthesis of difluoromethyl-containing pyrazoles, pyridines and pyrimidines

Domino Reactions of Chromone‐3‐carboxylic Acids with Aminoheterocycles: Synthesis of Heteroannulated Pyrido[2,3‐c]coumarins and their Optical and Biological Activity

“…Our starting point was the development of suitable conditions for the synthesis of pyrido [3,2-c]coumarin 3a by reaction of chromone-3-carboxylic acid 1a with aminopyrazole 2a (Scheme 1). The aminopyrazole 2a and related aminoheterocycles used in this study were prepared as previously reported in our work related to the synthesis of heteroannulated pyridines, [57][58][59][60][61][62][63][64] spirocyclic 1,4-dihydropyridine compounds, [65] and 3,4-fused coumarins. [66] The best yield of 3a (up to 90 %) was obtained under the conditions reported in entry 5 of Table 1 using acetic acid as solvent (14 h, 60°C).…”

New 4-fluoroalkyl substituted N-phenylpyrazoles: Synthesis promoted by DAST and multinuclear NMR analysis

“…The NMR literature data is limited in relation to CH 2 F and CHF 2 groups attached to pyrazole rings even for the most common substituted 3 and 5 positions [31][32][33][34]. In general, mono and difluoromethyl groups do not show great variation of chemical shifts in aromatic pyrazole ring independent of their positions in the heterocycle [35,36].…”

(Het)aryl Difluoromethyl‐Substituted β‐Alkoxyenones: Synthesis and Heterocyclizations

“…In this work, we considered another approach to difluorodi(het)arylmethanes, which also relied on the use of (het)aryl difluoro methyl‐substituted building blocks, namely, β‐alkoxyenones of the type 1 [X = (het)aryl, Scheme ]. It should be noted that heterocyclizations of various fluorinated β‐alkoxyenones 1 (X = H, F, Cl, CF 3 , CHF 2 ) were reported in recent publications descri‐bing synthesis of fluoroalkyl‐substituted pyrazoles, isoxazoles, and pyrimidines,, , as well as other heterocycles , . However, no examples of (het)aryl difluoromethyl ‐substituted enones of the type 1 were reported to date.…”