1: (2-bromobenzyl)phosphonic acid diethyl ester; 5-chloro-2-hydroxybenzaldehyde With potassium tert-butylate in tetrahydrofuran T=-10 - 20°C; Wittig-Horner reaction; 1 h; 2: acetic anhydride in tetrahydrofuran T=20°C; 1 h;

1: (2-bromobenzyl)phosphonic acid diethyl ester; 5-chloro-2-hydroxybenzaldehyde With potassium tert-butylate in tetrahydrofuran; toluene T=-10 - 0°C; Wittig-Horner Reaction; 2: acetic anhydride in tetrahydrofuran; toluene T=-5 - 20°C;

1: 4-chloro-2-hydroxy-benzaldehyde; (2-bromobenzyl)phosphonic acid diethyl ester With potassium tert-butylate in tetrahydrofuran T=-10 - 5°C; Wittig Reaction; 1 h; 2: acetic anhydride in tetrahydrofuran T=-5 - 20°C; 1 h;