Pyridine → (S)-(+)-6-benzyloxy-2,5,7,8-tetramethylchroman-2-carboxaldehyde

Participants

Reaction Steps

To a stirred mixture of 36 ml. of dry CH2Cl2, 2.8 ml. of dry pyridine and 1.46 g. (14.6 mmol) of CrO3 was added a solution of 645 mg. (1.98 mmol) of (S)-(-)-6-benzyloxy-2,5,7,8-tetramethylchroman-2-methanol in 5 ml. of CH2Cl2. The dark mixture was stirred for 40 min. at room temperature then the organic solution was decanted and the dark residue was washed with ether and CH2Cl2. The combined organic solutions were diluted with ether, washed with 1 N NaOH, H2O and 1 N HCl and work-up was then completed in the usual manner. The yellow oily product (590 mg.) was chromatographed on 50 g. of silica gel. Elution with 19:1 (parts by volume) hexane-ether gave 492 mg. (76.7%) of pure (S)-(+)-6-benzyloxy-2,5,7,8-tetramethylchroman-2-carboxyaldehyde as an oil which crystallized yielding a colorless solid, mp 56°-58°;[α]25D+ 11.89° (c 5.2, CHCl3).

Provenance & Evidence