1: acetonitrile With sodium hydride in 1,4-dioxane 0.333333 h; 2: 4-methoxybenzyl 3,3-difluorocyclobutanecarboxylate in 1,4-dioxane 4 h; Reflux;

1.1: DAST / dichloromethane / 20 °C 2.1: sodium hydride / 1,4-dioxane / 0.33 h 2.2: 4 h / |Reflux View Scheme

1.1: sodium hydrogencarbonate; tetrabutylammomium bromide / dichloromethane; water / 20 °C 2.1: DAST / dichloromethane / 20 °C 3.1: sodium hydride / 1,4-dioxane / 0.33 h 3.2: 4 h / |Reflux View Scheme