Diisopropylamine → ethyl (2S,3R)-3-hydroxy-2-octylbutyrate

Participants

Reaction Steps

A mixture of 83.5 g of diisopropylamine and 400 ml of tetrahydrofuran was treated dropwise at -20° C. within 30 minutes with 500 ml of a 1.6M solution of butyllithium (0.800 mol) in hexane. The mixture was stirred at -20° C. to -50° C. for a further 30 minutes. Subsequently, the mixture was treated dropwise at -50° C. within 30 minutes with a solution of 50 g (0.378 mol) of ethyl (3R)-3-hydroxybutyrate in 250 ml of tetrahydrofuran and stirred at -30° C. for a further 30 minutes. Thereafter, the reaction mixture was treated dropwise at -50° C. within 30 minutes with a solution of 108 g of 1-bromooctane (0.560 mol) in 96.5 g of hexamethylphosphoric acid triamide. The reaction mixture was left to warm to room temperature and was stirred at 25° C. for a further 3 hours. Subsequently, the brown reaction solution was poured into 1.3 l of water and extracted three times with ethyl acetate. The organic phases were washed with saturated sodium chloride solution, dried over sodium sulfate, filtered and concentrated. High vacuum distillation of the brown oil obtained (128 g) gave 54 g of ethyl (2S,3R)-3-hydroxy-2-octylbutyrate with b.p. 99° C./0.03 Torr and [a]D =+6.2° (c=1% in chloroform).

Provenance & Evidence