2-Hydroxy-2-trifluoromethylbutan-4-olides (8-10) were prepared by a four step synthesis starting from a ketone and methyl 3,3,3-trifluoropyruvate (1) as a building block. Uncatalyzed chemospecific aldolization of ketones with 1 afforded 2 hydroxy-4-oxoesters 2-4 that were selectively reduced at the oxo group by sodium borohydride to the corresponding 2,4-dihydroxyesters 5-7. Acid-catalyzed cyclization of dihydroxysters 5-7 to lactones 8-10 was strongly dependent on their structure. The lactone-ring closure with the hydroxy group at the hydroxylated cyclopentane ring afforded bicyclic lactone (10) with cyclopentane cis-annulation. 2-Hydroxy-2 trifluoromethylbutanolides appeared to be highly resistent to dehydration or eliminations of the corresponding mesylates or triflates. (C) 2001 Elsevier Science B.V. All rights reserved.
steps were verified for the three-component domino cyclisation affording (pyrrolo)quinazolines from 2-(aminomethyl)aniline, a very reactive oxo compound and “usual” oxo compound. The first step was a rapid reaction of very reactive oxo compound (trifluoropyruvate or hexafluoroacetone) with benzylic amino group to form hemiaminal, but not imine; the second step was the reaction of oxo compound with aromatic
A convenient two-step synthesis of 4-CF3-(2H)-pyridazin-3-ones starting from methyl 3,3,3-trifluoropyruvate (MeTFP) and carbonyl compounds has been elaborated. As a result, a set of various 4-CF3-(2H)-pyridazin-3-ones was obtained. The scope and limitations of the methodology is defined.