10.6084/m9.figshare.5303308 Wystan K. O. Teixeira Wystan K. O. Teixeira Helena A. Gonçalves Helena A. Gonçalves Débora L. de Mello Débora L. de Mello Sidnei Moura Sidnei Moura Darlene C. Flores Darlene C. Flores Alex F. C. Flores Alex F. C. Flores Cyclocondensation between fatty acid hydrazides and 1,1,1-trifluoro-4-alkoxy-3-alken-2-ones: Introducing a trifluoromethylated head onto fatty acid moieties Taylor & Francis Group 2017 1,1,1-Trifluoro-4-alkoxy-3-alken-2-ones 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-pyrazoles [3 + 2] cyclocondensation fatty hydrazides 2017-08-11 13:50:51 Journal contribution https://tandf.figshare.com/articles/journal_contribution/Cyclocondensation_between_fatty_acid_hydrazides_and_1_1_1-trifluoro-4-alkoxy-3-alken-2-ones_Introducing_a_trifluoromethylated_head_onto_fatty_acid_moieties/5303308 <p>This paper reports the regioselective synthesis of new trifluoromethylated lipid derivatives, namely, 1-(5-hydroxy-5-trifluoromethyl-3-alkyl-4,5-dihydro-1<i>H</i>-pyrazol-1-yl)alkan-1-ones, through cyclocondensation reactions between a series of fatty hydrazides (palmitoyl, stearoyl, and oleoyl hydrazides) obtained from fatty acids from renewable resources (1,1,1-trifluoro-4-alkoxy-3-alken-2-ones [F<sub>3</sub>CC(O)CH˭C(R<sup>1</sup>)OR, where R<sup>1</sup> = H and R˭Et; R<sup>1</sup> = –(CH<sub>2</sub>)<sub>6</sub>CH<sub>3</sub>, –(CH<sub>2</sub>)<sub>6</sub>CH<sub>3</sub>, –(CH<sub>2</sub>)<sub>8</sub>CH<sub>3</sub>, –(CH<sub>2</sub>)<sub>9</sub>CH<sub>3</sub>, –(CH<sub>2</sub>)<sub>10</sub>CH<sub>3</sub>, –(CH<sub>2</sub>)<sub>12</sub>CH<sub>3</sub>, –(CH<sub>2</sub>)<sub>2</sub>Ph], and R˭Me). Experimental observations showed that the lipophilic characteristic of 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1<i>H</i>-pyrazoles (<b>5–7</b>) prevent the acid catalyzed dehydration to aromatization of 1<i>H</i>-pyrazole ring, although in some cyclocondensations a proportion of the aromatic derivative 1-(5-trifluoromethyl-3-alkyl-1<i>H</i>-pyrazol-1-yl)alkan-1-one was obtained. All products were characterized using multinuclear (<sup>1</sup>H, <sup>13</sup>C, <sup>19</sup>F) NMR spectroscopy.</p>