Me 2-oxo-2-arylacetates, which include some fluorinated compds., have been synthesized in moderate to excellent yields by reaction of Me oxalyl chloride with arylzinc halides in the presence of Pd(PPh3)4. The highest yields have been obtained when these reactions involved arylzinc bromides which were prepd. by conversion of the corresponding aryl bromides to organolithiums, followed by transmetalation with ZnBr2. The 2-oxo-2-arylacetates have been converted in high yields to the corresponding (E)- and (Z)-O-methyloximino-2-arylacetates by treatment with O-methylhydroxylamine hydrochloride in pyridine. The oximes have been easily sepd. by MPLC on silica gel and their structure and stereochem. have been assigned by NMR techniques. The prepd. compds. included an agrochem. important fungicide, its fluorinated structural analogs, as well as compds. which proved to be able to delay the growth of fungal species isolated from deteriorated papers. Several (Z)-oximes underwent partial stereomutation in the presence of daylight and catalytic amts. of iodine.
A novel method for the efficient synthesis of methyl 2-oxo-2-arylacetates and its application to the preparation of fungicidal methyl (E)-O-methyloximino-2-arylacetates and their (Z)-stereoisomers
ROSSI, RENZO;CARPITA, ADRIANO;
1999-01-01
Abstract
Me 2-oxo-2-arylacetates, which include some fluorinated compds., have been synthesized in moderate to excellent yields by reaction of Me oxalyl chloride with arylzinc halides in the presence of Pd(PPh3)4. The highest yields have been obtained when these reactions involved arylzinc bromides which were prepd. by conversion of the corresponding aryl bromides to organolithiums, followed by transmetalation with ZnBr2. The 2-oxo-2-arylacetates have been converted in high yields to the corresponding (E)- and (Z)-O-methyloximino-2-arylacetates by treatment with O-methylhydroxylamine hydrochloride in pyridine. The oximes have been easily sepd. by MPLC on silica gel and their structure and stereochem. have been assigned by NMR techniques. The prepd. compds. included an agrochem. important fungicide, its fluorinated structural analogs, as well as compds. which proved to be able to delay the growth of fungal species isolated from deteriorated papers. Several (Z)-oximes underwent partial stereomutation in the presence of daylight and catalytic amts. of iodine.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
