Yield:-

Reaction Conditions:

Stage #1: (2,3-dimethylpyridin-4-yl)-methanolwith 4-methylmorpholine N-oxide in dichloromethane at 0; for 0.166667 h;Molecular sieve;
Stage #2: tetrapropylammonium perruthennate at 20; for 16 h;

Steps:

1.4 Step 4. 2,3-dimethylpyridine-4-carbaldehyde

A mixture of 4A molecular sieves (2.1 g) in dichloromethane (50 mL) is cooled to 0° C. under a nitrogen atmosphere. The alcohol from step 3 (1.96 g, 14.3 mmol) is added in one portion. 4-Methylmorpholine-N-oxide (3.35 g, 28.6 mmol) is added and the resulting solution stirred for 10 min at 0° C. Tetrapropylammonium perruthenate (266 mg, 0.76 mmol) is added in small portions and the mixture is stirred at room temperature for 16 h. The reaction mixture is filtered through silicagel, eluding with hexanes-EtOAc (1:1). Removal of the solvents under reduced pressure produces the title compound as a clear oil. ¹H NMR: 10.38 (s, 1H), 8.56 (d, 1H), 7.45 (d, 1H), 2.63 (s, 3H), 2.59 (s, 3H).

References:

US2005/239791,2005,A1 Location in patent:Page/Page column 21