Direct one-pot highly enantioselective assembly of polyketide and carbohydrate synthons

A short, direct, catalytic, enantioselective synthesis of polyketide segments and carbohydrates is presented. The novel, direct, one-pot, organocatalytic asymmetric tandem cross-aldol/Horner–Wittig–Emmons reactions assemble polyketide and carbohydrate derivatives in good yield with 93–98% ee. The one-pot catalytic asymmetric tandem reaction was applied to a highly enantioselective formal de novo synthesis of the rare carbohydrate, l-altrose.