Reaction #955944

Reaction equation

1,8-diazabicylo[5.4.0]undecene

benzyl bromide

→

8-benzyl-1,8-diazabicyclo[5.4.0]undecane

Yield 127.9%

Solvents

toluene

Conditions

Workup

1. 1
   OtherAn insoluble oil formed
2. 2
   workup.WAITAfter 4 hours
3. 3
   Filtrationthe solid was filtered
4. 4
   Otherdried

Procedure

A mixture of 34.0 g (0.2 mol) 1,8-diazabicylo[5.4.0]undecene and 200 mL toluene was mixed with 34.2 g (0.2 mol) benzyl bromide. An insoluble oil formed and then changed to a white solid as the temperature rose to 57° C. over 10 minutes. After 4 hours, the solid was filtered and dried to provide 62.5 g of 8-benzyl-1,8-diazabicyclo[5.4.0]undecane (the 8-benzyl salt of DBU, which was soluble in water). NaBH4 solution (1.58 g, 5.1 mmol, 4.4M NaBH4 in 14M NaOH solution, obtained from Alfa Aesar, Ward Hill, Mass.) was diluted with 10 mL water. Then, 15 mL t-butyl methyl ether (t-BuOMe) was added to the diluted solution, and the resulting mixture was magnetically stirred and cooled to 3° C. To the cooled mixture was added 3.23 g of the 8-benzyl salt of DBU prepared as described above. After 2 hours, the resulting cold mixture was phase split, the resulting aqueous layer was extracted with t-BuOMe, and the resulting t-BuOMe solutions were combined, dried, and stripped to yield 0.86 g of a product (photolatent catalyst mixture). Gas-liquid chromatographic (GLC) analysis of the product indicated that it contained 39 percent 8-benzyl-1,8-diazabicyclo[5.4.0]undecane (GLC area response with a thermal conductivity detector; identified by gas chromatography/mass spectrometry (GC/MS) analysis), 13 percent of N-3-benzylaminopropylazepine (identified by GC/MS and nuclear magnetic resonance (NMR) analysis), and 48 percent of what was believed to be N-(3-benzylaminopropyl)azepin-2-one (GC/MS mass of 262).

Source