Patent ID: 7772191

Claim:
Process for preparing the compounds of general formula III, wherein R 1 denotes cyclobutyl, cyclopentyl, cyclohexyl, R-tetrahydrofuran-3-yl, S-tetrahydrofuran-3-yl or tetrahydropyran-4-yl; and R 2 independently of one another denote hydrogen, (C 1-18 -alkyl)carbonyl, (C 1-18 -alkyl)oxycarbonyl, arylcarbonyl, aryl-(C 1-3 -alkyl)-carbonyl, aryl-C 1-3 -alkyl, allyl, R a R b R c Si, CR a R b OR c , wherein two adjacent groups R 2 may be linked with each other to form a bridging group SiR a R b , CR a R b or CR a OR b —CR a OR b ; and R′ denotes hydrogen, C 1-6 -alkyl, (C 1-4 -alkyl)carbonyl, (C 1-4 -alkyl)oxycarbonyl, arylcarbonyl, aryl-(C 1-3 -alkyl)-carbonyl; R a , R b , R c independently of one another denote C 1-4 -alkyl, aryl or aryl-C 1-3 -alkyl, while the alkyl groups may be mono- or polysubstituted by halogen; L1 independently of one another are selected from among fluorine, chlorine, bromine, C 1-3 -alkyl, C 1-4 -alkoxy and nitro; while by the aryl groups mentioned in the definition of the above groups are meant phenyl or naphthyl groups, which may be mono- or polysubstituted with L1; said method comprised of the step of adding an organometallic compound of the formula VI wherein R 1 is defined as hereinbefore and M denotes Li or MgHal, wherein Hal denotes Cl, Br or I; or a derivative thereof obtained by transmetallation; which compound of the formula VI may be obtained by halogen-metal exchange or by the insertion of a metal in the carbon-halogen bond of a halogen-benzylbenzene compound of general formula V wherein R 1 is defined as hereinbefore and X denotes Br or I; and optionally subsequent transmetallation, to a gluconolactone of general formula IV wherein R 2 is as hereinbefore defined, and reacting the adduct obtained with water or an alcohol R′—OH, where R′ denotes C 1-6 -alkyl, in the presence of an acid and optionally the product obtained in the reaction with water wherein R′ denotes H is converted in a subsequent reaction with an acylating agent into the product of formula III wherein R′ denotes (C 1-4 -alkyl)carbonyl, (C 1-4 -alkyl)oxycarbonyl, arylcarbonyl, or aryl-(C 1-3 -alkyl)-carbonyl, wherein the term aryl is defined as hereinbefore.