Unsatd. beta-oxy-carboxylic acid halide prepn. - from enol cpd. and oxalyl halide in 3 stages, used as intermediate for drugs, plant protectants, dyes or polymers

摘要

Prepn. of alpha, beta-unsatd. beta-oxy-carboxylic acid chlorides or bromides of formula R1O-C(R2)=C(R3)-CO-X (I) comprises: (i) addn. reaction of an enol deriv. of formula R1O-C(R2)=CHR3 (II) with an oxalyl dihalide of formula X-CO-CO-X (III); (ii) elimination of HX from the obtd. alpha-ketoacid halide of formula R1O-CXR2-CHR3-CO-COX (IV) to give the corresp. beta, gamma-unsatd. alpha-ketoacid halide of formula R1O-CR2=CR3-CO-CO-X (V); and (iii) decarboxylating (V) to give (I): X = Cl or Br; R1 = C-organic gp.; R2, R3 = H or C-organic gp. Prepn. of cpds. (IV) as in step (i) is separately claimed. Cpds. (I) are new where: R1 = phenyl or benzyl (both opt. ring-substd. by 1-5 halogen and/or 1-3 of 1-4C alkyl, 1-4C haloalkyl, 1-4C alkoxy, 1-4C haloalkoxy, 1-4C alkylthio and 1-4C haloalkylthio); and R2, R3 = H. The new cpds. pref. have the double bond in E-configuration. USE/ADVANTAGE - (I) are intermediates, e.g. for pharmaceuticals, plant protectants, dyes and polymers. (I) are obtd. simply and economically. Intermediates need not be isolated.