Three‐bond 13 C 1 H coupling constants for chrysanthemic acid and phenothrin metabolites: Detection by two‐dimensional long‐range 13 C 1 H J ‐resolution spectroscopy

Two‐dimensional long‐range 13 C 1 H J ‐resolution spectroscopy (LRCJR) was used to measure three‐bond 13 C 1 H coupling constants [ 3 J (C,H)] for trans ‐ and cis ‐chrysanthemic acid, methyl trans ‐pyrethrate and some microsomal metabolites of the trans ‐chrysanthemate biophenothrin. The carbon of the methyl cis ‐disposed to an attached proton shows a larger 3 J (C,H) value than does the trans ‐carbon for the dimethyl‐substituted cyclopropane and epoxide rings. The reverse situation applies for the analogous dimethyl vinyl grouping. The 3 J (C,H) values are not altered on conversion of one of the olefinic geminal methyl groups to a hydroxymethyl or methoxycarbonyl functionality, but increase on transformation to an aldehyde. These 3 J (C,H) values are in agreement previous results from long‐range CH COSY experiments, and provide a useful method for determining the stereochemistry of chrysanthemic acid derivatives.