p-Toluenesulfonic acid → (+)-(4S,trans)-1-[2-(2,4-dichlorophenyl)-4,5-dimethyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole

Participants

Reaction Steps

A mixture of 7.1 parts of 1-[2-(2,4-dichlorophenyl)-2,2-dimethoxyethyl]-1H-1,2,4-triazole 4-methylbenzenesulfonate, 1.5 parts of (2S,3S)-(+)-2,3-butanediol, 0.7 parts of 4-methylbenzenesulfonic acid and 68 parts of methylbenzene is stirred and refluxed for 3 days. The reaction mixture is cooled and alkalized with a sodium hydroxide solution 20%. The whole is poured onto water and the product is extracted with trichloromethane. The extract is dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using ethyl acetate as eluent. The pure fractions are collected and the eluent is evaporated. The residue is crystallized from a mixture of 2,2'-oxybispropane and petroleumether (1:1 by volume). The product is filtered off and dried, yielding 1.5 parts (31%) of (+)-(4S,trans)-1-[2-(2,4-dichlorophenyl)-4,5-dimethyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole; mp. 82.7° C.; [α]D =+30.47° (c=0.5 % CHCl3).

Provenance & Evidence