Reaction #3653

Reaction equation

5,6-dihydro-4H-[1,2,4]-triazolo-[4,3-a][1,5]benzodiazepin-5-one

borane dimethylsulfide

methanol

→

desired product

5,6-Dihydro-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepine

Solvents

tetrahydrofuran

tetrahydrofuran

Conditions

Workup

1. 1
   TemperatureThe mixture is refluxed for 6 hours
2. 2
   OtherThe volatiles are removed under vacuum and to the residue
3. 3
   workup.ADDITIONis added 100 ml of 2N sodium hydroxide
4. 4
   TemperatureThe mixture is refluxed for 5 hours
5. 5
   Temperaturechilled
6. 6
   Extractionextracted with dichloromethane
7. 7
   WashThe extract is washed with 2N citric acid, water
8. 8
   Dryingdried (Na2SO4)
9. 9
   OtherThe solvent is removed under vacuum
10. 10
    Otherto give a solid
11. 11
    OtherThe solid is purified by chromatography on silica gel

Procedure

A mixture of 7.0 g of 5,6-dihydro-4H-[1,2,4]-triazolo-[4,3-a][1,5]benzodiazepin-5-one in 25 ml of tetrahydrofuran is added 9 ml of 10M borane-dimethylsulfide in tetrahydrofuran. The mixture is refluxed for 6 hours, cooled to room temperature and 25 ml of methanol added dropwise. The volatiles are removed under vacuum and to the residue is added 100 ml of 2N sodium hydroxide. The mixture is refluxed for 5 hours, chilled and extracted with dichloromethane. The extract is washed with 2N citric acid, water and dried (Na2SO4). The solvent is removed under vacuum to give a solid. The solid is purified by chromatography on silica gel to give the desired product.

Source