1: (2R,4S)-3-[(4-methylphenyl)sulfonyl]-4-(phenylmethyl)-1,2,3-oxathiazolidine 2-oxide; 2,4,6-trimethylphenylmagnesium bromide in tetrahydrofuran T=-68°C; Inert atmosphereCooling with acetone-dry ice; 2: With lithium hexamethyldisilazane in tetrahydrofuran T=-68 - 20°C; Inert atmosphere; 3: benzaldehyde With titanium tetraethoxide in tetrahydrofuran T=20°C; Inert atmosphere; optical yield given as percent eeenantioselective reaction;