1: 2-(2,2-dimethoxyethyl)malonic acid diethyl ester With sodium hydride in tetrahydrofuran T=0 - 20°C; 2: diiodomethane in tetrahydrofuran 36 h; Heating;

1.1: NaOEt / ethanol / 0.5 h 1.2: 64 percent / ethanol / 36 h / Heating 2.1: NaH / tetrahydrofuran / 0 - 20 °C 2.2: 52 percent / tetrahydrofuran / 36 h / Heating View Scheme

toluene-4-sulfonic acid in acetone 2 h; Heating;