Method for the Production of 1,3-Dioxolane-2-Ones and Carboxylic Acid Esters by Means of Transacylation in Basic Reaction Conditions

A process for preparing tiotropium salts of formula 6

• wherein
• X− may represent an anion with a single negative charge selected from among the chloride, bromide, iodide, sulphate, phosphate, methanesulphonate, nitrate, maleate, acetate, citrate, fumarate, tartrate, oxalate, succinate, benzoate, p-toluenesulphonate and trifluoromethanesulphonate,
• comprising the steps of reacting a compound of formula 1
• wherein
• R1 and R2 both denote 2-thienyl and
• R3 denotes a group selected from among methyl, ethyl, propyl, isopropyl, isopropenyl, butyl, —N-succinimide, —N-phthalimide, phenyl, nitrophenyl, fluorophenyl, pentafluorophenyl, vinyl, 2-allyl, in one step with a compound of formula 7
• wherein
• Y− denotes hexafluorophosphate,
• and with a compound of formula 2, in a solvent, with the addition of a basic catalyst in the form of a tert.-alkoxide in the presence of zeolite, to form a compound of formula 8
• wherein the group Y− has the meaning given hereinbefore, and
• converting the compound of formula 8 into the compound of formula 6 without isolation, by reacting with a salt Kat+X−, where Kat+ denotes a cation selected from among Li+, Na+, K+, Mg2+, Ca2+, organic cations with quaternary N (e.g. N,N-dialkylimidazolium, tetraalkylammonium), and X− may have the meanings given above.