| 摘要 |
<p>Lactones of formula (III) are reacted with a halogenating agent and then with an alcohol of formula R3OH, or the lactones (III) are reacted with the halogenating agent in the presence of the alcohol to yield cpds. of formula (II). The cpds. (II) are reacted with a base to yield 2,2-dimethyl-3-(2,2-dihalovinyl)cyclopropanecarboxylic acid derivs. (I) which are known insecticides. where X is the same or different halogen atom; one of R1 and R2 is Cl or Br and the other is -CH2COOR3 (R3 is lower alkyl), one of Y1 and Y2 is O and the other is -CH2-). The starting cpds. (III) are novel and may be prepd. from Me2C=CHCH2OH and MeC(OR3)3 via 3 steps. The halogenating agent involves SOCl2, PCl3, PBr3, HBr, HCl, SOBr2, etc. The alcohol involves MeOH, EtOH, PrOH, BuOH, etc. The base used in the 2nd step involves alkali metal alkoxide such as sodium alkoxide or t-BuOK. In the 1st steps, reaction is conducted in a solvent (e.g. petroleum ether, petroleum benzene, xylene, hexane, benzene, toluene, THF) at 0 degrees C to the b.pt. of the solvent used for 30 mins. to 20 hrs. In the 2nd step, the reaction is conducted in a solvent (e.g. alcohol, THF, Et2O, benzene, toluene) at a temp. around the b.pt. of the solvent used for 30 mins. to 10 hrs.</p> |
