Reaction #355763

Reaction equation

K2CO3

2,6-bis-pyridyl-4-(1H)-pyridone

phosphorus pentabromide

phosphorus oxybromide

→

4′-bromo-2,2′;6′,2″-terpyridine

2,6-bis-pyridyl-4-(1H)-pyridone

Conditions

Workup

1. 1
   Othergiving a black oily residue
2. 2
   TemperatureThe reaction was cooled to room temperature
3. 3
   workup.ADDITIONice was added cautiously to the reaction until the evolution of gas
4. 4
   Extractionextracted with CH2Cl2 (3×300 mL)
5. 5
   Dryingdried over MgSO4
6. 6
   Filtrationfiltered
7. 7
   OtherRemoval of solvent
8. 8
   Othergave a tan colored solid which
9. 9
   Otherwas purified by column chromatography on neutral alumina using 2:1 CH2Cl2

Procedure

A 500 mL flask was charged with 2,6-bis-pyridyl-4-(1H)-pyridone (2.47 g, 9.9 mmol), phosphorus pentabromide (6.6 g, 15.4 mmol), and phosphorus oxybromide (30 g) and heated to 100° C. with stirring for 12 h, giving a black oily residue. The reaction was cooled to room temperature; ice was added cautiously to the reaction until the evolution of gas subsided. The reaction mixture was neutralized with K2CO3 (aq), extracted with CH2Cl2 (3×300 mL), dried over MgSO4, and filtered. Removal of solvent gave a tan colored solid which was purified by column chromatography on neutral alumina using 2:1 CH2Cl2:hexanes as the eluant, providing 2.65 g of pure 4′-bromo-2,2′;6′,2″-terpyridine (86% yield, based on 2.47 g of the 2,6-bis-pyridyl-4-(1H)-pyridone starting material). 1H-NMR (250 MHz, CDCl3): 8.68 (dq, 2 H, J=4.7 Hz, 0.8 Hz), 8.62 (s, 2 H), 8.56 (dt, 2 H, J=8.0 Hz, 1.0 Hz), 7.84 (td, J=7.7 Hz, 1.7 Hz), 7.33 (ddd, 2 H, J=7.6 Hz, 4.9 Hz, 1.2 Hz). HRMS (ESI+) m/z: 333.9955 (calcd for C15H10N3BrNa (M+Na)+ 333.9956).

Source