Reaction #73062

Reaction equation

triethyl orthoformate

2,2-dimethyl-[1,3]-dioxane-4,6-dione

3-Amino-5-bromopyridine

→

5-{[(5-bromopyridin-3-yl)imino]methyl}-2,2-dimethyl-1,3-dioxane-4,6-dione

Solvents

ethanol

Conditions

Workup

1. 1
   Temperaturecooled to 70° C. over one hour
2. 2
   Washrinse
3. 3
   Temperaturewhile maintaining the reaction temperature between 60 and 70° C
4. 4
   TemperatureThe reaction was then heated for an additional 20 minutes
5. 5
   Temperatureto cool to room temperature
6. 6
   FiltrationThe reaction mixture was filtered
7. 7
   Washwashed with ethanol (150 mL)
8. 8
   Otheryielding a tan solid
9. 9
   OtherThe solid was dried under vacuum for 2 hours

Procedure

A mixture of triethyl orthoformate (10 mL, 60.1 mmol) and 2,2-dimethyl-[1,3]-dioxane-4,6-dione (40.9 g, 0.23 mol) (Meldrum's acid) was heated at 92° C. for 90 minutes and then cooled to 70° C. over one hour. 3-Amino-5-bromopyridine (40.9 g, 0.20 mol) was slowly added over 10 minutes with an ethanol rinse while maintaining the reaction temperature between 60 and 70° C. The reaction was then heated for an additional 20 minutes and allowed to cool to room temperature. The reaction mixture was filtered and washed with ethanol (150 mL) yielding a tan solid. The solid was dried under vacuum for 2 hours to yield 59.14 g of 5-{[(5-bromopyridin-3-yl)imino]methyl}-2,2-dimethyl-1,3-dioxane-4,6-dione as a light yellow crystalline solid, mp 200-202° C.

Source