2,2-Dimethyl-1,3-dioxane-4,6-dione → 5-(5-Bromopyridin-2(1H)-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione

Participants

Reaction Steps

3-Bromopyridine N-oxide (10 g, 57.5 mmol) was slowly added into a solution of 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid, 8.28 g, 57.5 mmol) in acetic anhydride (58 mL) at 0° C. The temperature was allowed to come to room temperature overnight. The mixture was filtered and yellow crystals were washed with small amount of acetic anhydride and dried in vacuo. The residue was triturated with warm chloroform and insoluble residue was filtered off. The chloroform soluble fraction was evaporated and the residue triturated with 5% MeOH in DCM. The solid material was filtered off and the soluble fraction was evaporated to give 3.55 g (20%) of 5-(5-Bromopyridin-2(1H)-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione. 1H NMR (400 MHz, dMSO): δ 1.61 (s, 6H), 1.64 (s, 1H), 8.20-8.23 (dd, 1H), 8.51-8.52 (d, 1H), 8.62-8.65 (d, 1H).

Provenance & Evidence