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Preparation of all stereoisomers of 14 C‐labelled 3‐(2,2‐dichloroethenyl)‐and 3‐(2,2‐dibromoethenyl)‐2,2‐dimethylcyclopropanecarboxylic acids
Author(s) -
Kanamaru Hiroshi,
Kawahara Kazuo,
Okuno Masami,
Yoshitake Akira,
Nakatsuka Iwao
Publication year - 1987
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.2580240408
Subject(s) - chemistry , wittig reaction , phosphorane , sodium periodate , hydrolysis , osmium tetroxide , yield (engineering) , high performance liquid chromatography , ylide , stereochemistry , organic chemistry , medicinal chemistry , electron microscope , physics , materials science , optics , metallurgy
The four 14 C‐labelled stereoisomers of both 3‐(2,2‐dichloroethenyl)‐2,2‐dimethylcyclopropanecarboxylic acid and 3‐(2,2‐dibromoethenyl)‐2,2‐dimethylcyclopropanecarboxylic acid, the improtant acid components of various potent insecticidal pyrethroids, were prepared efficiently from [1‐ 14 C]chrysanthemic acid ( 5 ) for use in comparative metabolic studies. α‐Bromo‐β‐naphthyl d,l‐cis, trans ‐[1‐ 14 C]chrysanthemate ( 6 ) was oxidized with osmium tetroxide‐sodium periodate to give the formyl ester ( 7 ) in 78% yield. Wittig reaction of 7 with dichloromethylenetris(dimethylamino)phosphorane at −75 ‐ −70 °C afforded the dichlorovinylated ester ( 8 ) quantitatively. Optical resolution of 8 by preparative HPLC using a chiral‐phase column led to the four stereoisomers ( 8a ‐ 8d ) with optical purities more than 99%. Hydrolyses of the esters ( 8a ‐ 8d ) yielded the corresponding optically active 3‐(2,2‐dichloroethenyl)‐2,2‐dimethyl [1‐ 14 C]cyclopropanecarboxylic acids ( 1a ‐ 1d ) quantitatively. Similarly, Wittig reaction of the formyl ester ( 7 ) with dibromomethylenetris(dimethylamino)phosphorane, followed by optical resolution and hydrolysis, gave four optically active 3‐(2,2‐dibromoethenyl)‐2,2‐dimethyl [1‐ 14 C]cyclopropanecarboxylic acids ( 2a ‐ 2d ) in considerably high yields.