The Boekelheide Reaction: Trifluoroacetic Anhydride as a Convenient Acylating Agent

Efficient Access to C1‐ and C3‐Functionalized Isoquinolines: Towards Potential Lanthanide Ligands

“…After N-oxidation of the isoquinoline ring, the N-oxide was submitted to rearrangement in the presence of acetic anhydride [25] followed by basic treatment to afford a 1,3-dihydroxymethylisoquinoline (Scheme 3). [26] Scheme 3. Attempts to oxidize 4.…”

The synthesis of a series of adenosine A3receptor agonists

“…When this N-oxide was reacted with an excess of acetic anhydride, standard conditions for effecting regioselective hydroxylation of a methyl group ortho to an N-oxide, 8,12 a mixture of several products was obtained. However, the use of trifluoroacetic anhydride in dichloromethane under reflux, 13 followed by saponification, gave a single product 15 in which the methyl group remote from the Noxide had been hydroxylated, albeit in only a modest yield, see Scheme 1.…”

“…100%) used without purification, Rf 0. 13 Sodium nitrite (1.47 g, 21.3 mmol, 1.1 eq) in water (15 mL) was added over a period of 7 min to 5-amino-2,4-lutidine (10) (2.37 g, 19.4 mmol) in aqueous sulfuric acid (4.8%, 37.8 mL) cooled to 0 °C using dry ice/acetone bath. The solution was maintained at 0 °C for 15 min and then heated under reflux for 5 min.…”

“…1 H and 13 C NMR spectra were recorded on Varian Unity Inova 400 and Varian Unity Inova 300 spectrometers with residual nondeuterated solvent as the internal standard. Only distinguishable peaks are reported for minor isomers in isomeric mixtures.…”

Total Synthesis of Thiostrepton, Part 2: Construction of the Quinaldic Acid Macrocycle and Final Stages of the Synthesis

“…Thus, 9 was converted in five steps and good overall yield as previously described [3] into functionalized methyl ester 10. The latter compound was then oxygenated to afford 11 in 65 % overall yield through a Boekelheide-type sequence [4] involving a) MCPBA-mediated N-oxide formation; b) TFAA-induced acylation of the generated N-oxide; and c) NaHCO 3 -facilitated rearrangement-hydrolysis of the resulting trifluoroacetate. Alcohol 11 was then dehydrated by treatment with Burgess reagent to afford olefin 12 in 68 % yield.…”