Reaction #7243

Reaction equation

CH3OH

isoquinoline-3-carboxylic acid

BH3-THF

→

3-(hydroxymethyl)isoquinoline

Yield 12.3%

Solvents

THF

Conditions

Workup

1. 1
   workup.STIRRINGwith stirring for a further 24 hrs
2. 2
   ConcentrationThe mixture was concentrated
3. 3
   workup.ADDITIONthe residue was treated with dry CH3OH (3×10 mL)
4. 4
   Otherremoving the solvent
5. 5
   Otherby evaporation each time
6. 6
   OtherThe crude product was purified by column chromatography (12 g silica gel, 19:1 CH2Cl2: CH3OH)

Procedure

To a stirred solution of isoquinoline-3-carboxylic acid (0.3179 g, 1.84 mmol) in dry THF (10 mL) at room temperature was added BH3-THF (1.0 M, 7.5 mL, 7.5 mmol). The mixture was stirred for 17 hrs, dry CH3OH (10 mL) was added, and the reaction was heated to 0.75° C. with stirring for a further 24 hrs. The mixture was concentrated and the residue was treated with dry CH3OH (3×10 mL), removing the solvent by evaporation each time. The crude product was purified by column chromatography (12 g silica gel, 19:1 CH2Cl2: CH3OH) to give 0.0359 g of 3-(hydroxymethyl)isoquinoline as a white film. The solid was dissolved in dry CH2Cl2 (5 mL) and treated with MnO2 (˜85%, 0.2978 g, 2.91 mmol) with stirring for 19 hrs then filtered through celite. Concentration of the filtrate afforded 0.0252 g (9%) of isoquinoline-3-carboxaldehyde as yellow oil. 1H NMR (CDCl3) d 7.73–7.82 (m, 2H), 7.97–8.07 (m, 2H), 8.37 (s, 1H), 9.36 (s, 1H), 10.25 (s, 1H).

Source