The invention provides an improved process for the preparation of a lower alkyl ester of 3-(2-chloro-3,3,3-trifluoroprop-1-en-1-yl)-2,2-dimethylcyclopropane carboxylic acid in which the corresponding lower alkyl ester of a carboxylic acid selected from 6-bromo-6-chloro-3,3-dimethyl-7,7,7-trifluorohept-2-enoic acid and 6,6-dichloro-3,3-dimethyl-7,7,7-trifluorohept-2-enoic acid is treated with an alkali metal lower alkoxylate in the presence of an aromatic hydrocarbon solvent under conditions under which the lower alcohol of the alkoxylate is removed from the reaction mixture by distillation with the aromatic solvent. The products are useful as intermediates in the manufacture of pyrethroid insecticides.
The invention discloses a process for the preparation of a halogenated alcohol of formula: CF.sub.3 --CXCl--CH(OH)--CH.dbd.C(CH.sub.3).sub.2 wherein X is bromo or chloro which comprises reacting a compound of formula: CF.sub.3 CHXCl with 3-methylbut-2-en-1-al in the presence of a strong base and an inert solvent. The products are useful intermediates for the manufacture of insecticides.
The present invention relates to compounds and pharmaceutical preparations and their use in therapy for preventing or treating trauma, ischemia, stroke and degenerative diseases associated with cell death. Methods and compositions of the invention are particularly useful for treating neurological disorders associated with cellular necrosis.
Gas-phase thermolyses. Part 3. Gas-phase thermolysis of silylated thionocarboxylic acid derivatives: a route to thioketens?
作者:Lars Carlsen、Helge Egsgaard、Ernst Schaumann、Herbert Mrotzek、Wolf-R�diger Klein
DOI:10.1039/p29800001557
日期:——
The unimolecular gas-phase thermolytic decomposition of three silylated thionocarboxylic acid derivatives (2b), (3), and (8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range from 783 to 1 404 K in order to elucidate its possible applicability as a route to thioketens. Only very minor amounts of the expected thioketens were found