A new and efficient manufacturing technology is disclosed in the present work for the preparation of picoxystrobin in which all of the intermediates can be used directly in the next step of the process without purification.
A facile, six-step process for the synthesis of (3S,5S)-3-isopropyl-5-((2S,4S)-4-isopropyl-5-oxotetrahydro-furan-2yl)-2-oxopyrrolidine-1-carboxylic acid tert-butyl ester from (S)-4-benzyloxazolidin-2-one 2 in an overall 50% yield is reported.The key transformations include: a highly efficient diastereoselective epoxidation, Lewis acid-catalyzed ring-opening with bromide, an S N 2 reaction using NaN 3 , and a tandem reduction−cyclization reaction.
A chiral β-amino acid derivative was synthesised by a cobalt-catalysed alkylation of 2,4,5-trifluorophenyl magnesium bromide with the alkyl halide derivative of L-aspartic acid, using an efficient catalytic reagent: CoCl 2 /TMEDA. The halide derivative was synthesised from protected L-aspartic acid β-methyl ester and the Grignard reagent was made by bromine-magnesium exchange. The stereo-structure was well preserved from L-aspartic acid.
A novel synthetic route to chiral β-amino acid derivative has been developed by a Grignard reaction of 2,4,5-trifluorophenyl magnesium bromide with the Weinreb amide derivative of L-aspartic acid. The aspartic equivalent was synthesised from L-aspartic acid in four steps, and the Grignard reagent was prepared by Br-Mg-exchange reaction. The target compound was achieved after the Grignard reaction and a subsequent reduction. Tthe stereo structure of the chiral amine was well preserved from the L-aspartic acid.
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