aldehydo-L-arabinose → Methyl beta-L-arabinopyranoside

Participants

Reaction Steps

To a suspension of L-arabinose (100 g, 667 mmol) in anhydrous MeOH (450 mL) was added a HCl/MeOH solution (7.3 g dry HCl in 50 mL MeOH) at room temperature under argon atmosphere. The mixture was refluxed for 2 h and cooled down to room temperature. The solution was concentrated to about ¾ of its volume to give a suspension. The solid precipitated was filtered and washed with cold MeOH (20 mL) to give the first crop as a crystalline powder (35.23 g). The filtrate was concentrated (35° C.) to ¼ of its volume. The solid precipitated was filtered, washed and dried as above to give the second crop (9.66 g) as a colorless crystalline powder. The concentration and filtration were repeated to afford additional 28.31 g of the product (total 73.2 g, 67%). 1H NMR (D2O) δ3.30 (s, OCH3, 3H), 3.56 (dd, 1H, H5), 3.73 (m, 1H, H4), 3.77 (dd, 1H, H5), 3.82 (bs, 1H, H2), 4.73 (m, 1H, H1).

Provenance & Evidence