An asymmetric total synthesis of a potent immunosuppressant, mycestericinsD and F, through an aldol reaction using L-threonine aldolase

L-Threonine aldolase from Candida humicola catalyzed the aldol reaction of 4-benzyloxybutanal (1) with glycine to give beta-hydroxy-alpha-amino acids (2e,t), whose erythro / three ratio was controlled by using either kinetic or thermodynamic conditions. The erythro derivative (4e) was effectively co nverted to mycestericins D and F via a stereoselective hydroxymethylation o f oxazoline derivative (6) as the key step.