| abstract |
Disclosed herein is a method for preparing 3-oxo-tetrahydrothiophene derivatives of formula 6, comprising the steps of: a) reacting reagents of the formulas HS-CH2-CO2Ra and CHR5=CR4-CO2Ra to obtain an intermediate of formula 7, b) cyclising the intermediate of formula 7 in a solvent and in the presence of TiCl2(OiPr)2, TiCl(OiPr)3, TiCl3(OiPr) (Titanium Chloride Isopropyl compounds) or chiral variants thereof and in the presence of an amine base to obtain the intermediate of formula 6, wherein the substitutents are as defined within the specification and further wherein the intermediate of formula 6 maybe used in a subsequent reaction step without the need for chromographic purification in that step or optionally , all steps thereafter. |