Resolution of di:methyl-di:halovinyl-cyclopropane-carboxylic acids - using ephedrine, N-methyl-ephedrine or pseudo-ephedrine, useful as intermediates for insecticidal ester(s)

摘要

Optical resolution of racemic (cis or trans) cpds. of formula (I): (where X is F, Cl or Br) is carried out by (a) reacting racemic (I) with an optically active base (II) selected from D-(I) and L-ephedrine, D- and L-N-methylephedrine and D- and L-pseeudoephedrine, (B) isolating the resulting crystallised salt, and (c) decomposing the salt by acid hydrolysis. The salts of D- and L-cis and D-and L-trans cpds. (I) with (II) are new. The optical isomers of (I) are useful as intermediates for insecticidal esters. The process uses less expensive base than the processes of JA131953/75, 143647/76 and 036441/76, and gives good yields.