Boron trihalide-promoted addition of aryl aldehydes to styrenes. A new convenient and highly efficient synthesis of 1,3-dihalo-1,3-diarylpropanes

Reactions of aryl aldehydes with styrenes in the presence of boron trichloride in CH2Cl2 at 0°C produce 1,3-dichloro-1,3-diarylpropanes in excellent yields. Reactions carried out using boron tribromide generate the corresponding 1,3-dibromo-1,3-diarylpropane in good yields.