[H-].[H-].COCCO[Al+]OCCOC.[Na+].N1CCOCC1.[CH3:21][O:22][CH2:23][O:24][CH2:25][C:26]1[N:31]2[CH:32]=[CH:33][N:34]=[C:30]2[C:29]([C:35](OC)=[O:36])=[CH:28][CH:27]=1>C1(C)C=CC=CC=1>[CH3:21][O:22][CH2:23][O:24][CH2:25][C:26]1[N:31]2[CH:32]=[CH:33][N:34]=[C:30]2[C:29]([CH:35]=[O:36])=[CH:28][CH:27]=1
To a stirred solution of sodium bis(2-methoxyethoxy)aluminium dihydride (65% wt. in toluene, 0.512 mL, 1.678 mmol) at 0° C. under a nitrogen atmosphere was added a solution of morpholine (0.147 mL, 1.678 mmol) in toluene (3.35 mL) dropwise over 15 min to give a solution of reducing agent (approx 4 mL, 4 eq). An aliquot of this solution (1.5 mL, ca 1.5 eq) was added dropwise over 2 min to a stirred solution of impure methyl 5-({[(methyloxy)methyl]oxy}methyl)imidazo[1,2-a]pyridine-8-carboxylate (105 mg, 0.420 mmol) in toluene (4 mL) at −40° C. The reaction was stirred at −40° C. for 40 min when LCMS indicated that the ester had been reduced to the aldehyde. The reaction was quenched carefully by addition of water (2 mL) and then allowed to warm to ambient temperature and concentrated in vacuo. The residue was pre-absorbed on florosil (100-200 mesh) and purified on a silica cartridge (20 g) using a 0-25% methanol-DCM gradient over 40 min. The appropriate fractions were combined and concentrated in vacuo to give impure 5-({[(methyloxy)methyl]oxy}methyl)imidazo[1,2-a]pyridine-8-carbaldehyde as a yellow oil (52 mg) which was used directly in the next step.
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