Barium trifluoroacetates, preparation

This intermediate was alkylated with tert. -butyI-cj-iodohexanoate to the ester 30. Conversion to the acid 31 was achieved by cleavage of the fed.-butylester with trifluoroacetic acid at low temperature. The triple bond was reduced to a trans-double bond and simultanously the benzylether groups had been removed with lithium in ethylamine, under formation of the desired 15-deoxy-7-oxaprostaglandin Fla 32 in crystalline form. The ds-isomer was prepared by first reducing the triple bond of compound 30 with palladium on barium sulfate to 33, removal of the ted. -butylgroup with formic acid to 34 and debenzylation of the acid with lithium in ethylamine to 35. 

Alkylation of dimethyl ( S)-malate (2) at oxygen can be accomplished with an alkyl halide in the presence of silver oxide. The methoxy derivative 7a forms in 74% yield [3], while the benzyloxy analog 7b is produced in 84% yield [12]. Alternatively, 7b can be prepared by treating 2 with (9-benzyl trichloroacetimidate in the presence of trifluoroacetic acid (68% yield) [13]. Upon treatment of malate ester 7a with barium hydroxide, (iS)-methoxysuccinic acid (8) is obtained in high yield [3]. 

Using this chemical phenomenon, heavy-metal fluoride glasses were prepared using trifluoroacetates of zirconium, barium, lanthanum, aluminum and sodium [21]. Eigure 10.2 shows thermal gravimetric analysis of the ZBLAN powder in this process. A drastic decrease in weight (47.4%) was observed in the range of 220-300 °C, which was attributed to the decomposition from the trifluoroacetate to the sohd ZBLAN fluoride. 

---