Fluoral -acetal

Figure 2.33 Nucleophilic trifluoromethylation with (0,A/)-acetals of fluoral. ...

Imines and (Af,(9)-acetals from fluoral are useful precursors of trifluoromethyl nitrogen-containing molecules amines, amino alcohols, amino acids, peptidomimetic units, heterocycles, and so on (Figure 2.50). These simple Af-derivatives of fluoral are easily prepared from the hydrate or the hemiacetal. Imines of fluoral react in [2 + 1 ]... 

As summarized already in the introduction these iminium salts of fluoral are readily available either with trifluoroacetic acid anhydride (TFAA) and N-oxide of trifluoroethylamine (Potier-Polonowsky reaction, ref. 15) or from N-0 or N-S acetals formerly accessible by electrochemical amine oxidation and now by hydride reduction of thioamidinum salts (ref. 11). 

FLUORAL (7681-49-4) Reacts with acids, forming hydrogen fluoride. Aqueous solution attacks glass, and reacts violently with xenon hexafluoride. Aqueous solution is incompatible with sulfuric acid, caustics, ammonia, aliphatic amines, alkanolamines, amides, organic anhydrides, isocyanates, vinyl acetate, alkylene oxides, epichlorohydrin. 

A similar reaction was used for preparation of the remote stereocenter in 85, an intermediate in Paterson s synthesis of aurisides A and B. The asymmetric catalysis of the aldol reaction with fluoral has also been investigated by Mikami for highly enantioselective syntheses of fluorine-containing aldols. The reaction of the ketene trimethylsilyl acetal 86 with fluoral (87) in the presence of the BfNOL-catalyst 67 yielded the aldol adduct 88 in moderate yield (56%) and high enantioselectivity (90% ee). 

Figure 4. Gas Chromatogram of Tertiary Butoxide Initictea Acetate Endcapped Fluoral Oligomers...

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