Notes

Abstract

RCO-CF-COR' (111) HO*CH,*CHFCO,Et I CH,.OH (Iv) CH,:CPCO,Et (V) p-C,H,(CO)aNCH,CF(CO,Et),and R = R' = NH,). Alkaline cleavage of the ester (11; R = CHCl,, R' = OEt) gave the expected ethyl a-fluoro-p-hydroxypropionate (111) which was converted, without isolation, into its methanesulphonate. However, reaction of the latter with potassiophthalimide in dimethylformamide only decomposed the methanesulphonate to ethyl a-fluoroacrylate (IV). On the other hand, reaction of potassiophthalimide with the methanesulphonate from the hydroxymethyl derivative (11; R = R' = OEt) proceeded normally; hydrolysis of the product (V) with hydrochloric acid gave the desired aminoacid (I) in the form of its hydrochloride. Chromatography showed that the acid was homogeneous and that its RF values in two solvent systems were identical with those found for Heidelberger's product.1 A sample was kindly put at the disposal of Dr. Th. Winnick (Weizmann Institute of Science) by Dr. C. Heidelberger. We are indebted to Dr. Th. Winnick for the chromatographic identification.Experimental.-EthyZ yy-dichloro-a-fEuoraacetoacetate. To a stirred suspension of sodium hydride (12 g.) in anhydrous ether (350 ml.) a mixture of ethyl fluoroacetate (53 g.) and ethyl dichloroacetate (109 g.) was added dropwise a t such a rate that the mixture refluxed gently.Heating was continued on a water-bath for 4 hr. ; then the mixture was cooled and poured on sulphuric acid (50 g.) and ice. The ethereal layer was separated and the aqueous phase extracted twice with ether. The combined ether extracts were washed with sodium hydrogen carbonate solution, dried (Na,SO,), and distilled. The jwoduct (64 g., 59%) distilled a t 75-80°/0-2 mm. and had nD26 1.4555 (Found: C, 33.3; H, 3.3; F, 8.7. C,H,CI,FO, requires C, 33.2; H, 3 . 2 ; F, 8.7%).Fluoromalondianzide. The following recipe is based on previous observations. Ethyl chloroformate (217 g.) was added, dropwise and with stirring, to a cooled suspension of the sodio-enolate of ethyl fluoroacetate [from the ester (212 g.) and sodium hydride (48 g.)] in ether (1 l.), and the mixture was refluxed for 5 hr. After addition of water, the ether layer was separated and the aqueous phase extracted twice with ether. Distillation of the combined ethereal solutions permitted the recovery of unchanged ethyl fluoroacetate (80 g., 38%). The oily residue (ethyl fluoromalonate and fluoro-fluoroacetylmalonate) was added, a t 5-10', to a stirred aqueous 28% ammonia solution (500 ml.). After 21 hr. a t the same temperature, the precipitate (50 g., 21%, or 34% calc. on the unrecovered fluoroacetate) was filtered off, washed with methanol, acetone, and ether and dried. Ethyl yy-dichloro-ct-fE~oro-a-hydroxymet~zyZ-~-oxobzstyrute (I1Piperidine (1 ml.) and formic acid (6 drops) were added to a stirred mixture of ethyl yy-dichloroa-fluoroacetoacetate (115 g.) and paraformaldehyde (16 g.). The mixture was heated on a boiling-water bath until a clear solution resulted, then cooled and distilled. The hydroxymethyl compound (95 g . , 73%) distilled a t ...

Organic Fluorine Chemistry

“…(304) Claisen condensation of esters with ketones and of esters with esters are some of the most important synthetic routes to fluorinated products or intermediates. The former reaction leads to fluorinated ,B-diketones [498,499), the latter to fluorinated ,B-ketoesters [500][501][502][503][504][505]. (306) CHaCOCHa CF3C02C2Hs CHaCOCFa r EtONa, Et20, reflux 50 hr EtONa, Et20, reflux 50 hrl [498] 'f [499) 'f [498] CF3COCH2COCH3 70% j 75% CF3COCH2COCFa [504] Ketonic fission of fluorinated f1-ketoesters is an easy way to fluorinated ketones (Table 46) [505].…”

Organic Fluorine Compounds: Part XXX: Experiments in the Fluoroglutaric Acid Series

“…The reaction of diethyl fluoromalonate with acrylonitrile [3] gave erratic results; fluoromalondiamide -which is also more easily accessible than diethyl fluoromalonate [4] -on the other hand, gave a 90% yield of the adduct (I), using sodium methoxide as catalyst.…”

“…Equally, the methylol derivatives (VI, VII) of ethyl cc,y-difluoroacetoacetate and y,y-dichloro-cc-fluoroacetoacetate [4] reacted with diethyl malonate to give (Y), but no analogous reaction occurred with diethyl acetamidomalonate. The methylol derivative (VIII) of diethyl fluoromalonate gave with ammonia only the corresponding diamide (IX), no reaction taking place at the hydroxyl group.…”