H. Kanamaru, K. Kawahara, Masami Okuno
Apr 1, 1987
Citations
0
Influential Citations
0
Citations
Journal
Journal of Labelled Compounds and Radiopharmaceuticals
Abstract
The four 14C-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 [1-14C]chrysanthemic acid (5) for use in comparative metabolic studies. α-Bromo-β-naphthyl d,l-cis, trans-[1-14C]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 [1-14C]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 [1-14C]cyclopropanecarboxylic acids (2a - 2d) in considerably high yields.