Verfahren zur Herstellung von Thietanonen

摘要

It is known that thietanones of general formula (I), in which R<1>-R<4> have the meanings given in the description, can be produced by the cyclisation, using hydrogen sulphide and a base, of the adducts obtainable by the addition of bromine to the ketones of general formula (III) given in the description. The invention obviates the need for toxic hydrogen sulphide and bromine by cyclising beta -oxosulphenyls of general formula (II), in which R<1>-R<4> have the meanings indicated in the description and X represents Cl, Br or J, in an organic solvent under the influence of a base. The invention also concerns intermediate products for the synthesis of dipeptide sweeteners.