Efficient hydrolysis of dithioacetals by the N-fluoro-2,4,6-trimethylpyridinium triflate-water system
摘要:
Dithioacetals including 1,3-dithianes and 1,3-dithiolanes are efficiently cleaved by the title reagent system to the parent carbonyl compounds. The cleavage of diprotected symmetrical alpha-diketones and p-phenylene-diketones gives monoketones in good yields. Amide, 1,3-dioxolane, disulfide, ester, ether, hydroxy, nitrile, nitro, and sulfide functions are relatively stable under the cleavage conditions but thiols are oxidized to disulfides.
In the reaction of 2-ethoxy-1,3-oxathiolane with carbonylcompounds in the presence of ZnCl2 or HgCl2, it has been found that only the breaking of the endocyclic bond (C–O or C–S bond) occurs, while the breaking of the exocyclic C–O bond to give the 1,3-oxathiolan-2-ium ion is unfavorable. This behavior is different from that of 2-ethoxy-1,3-dithiolane, in which the breaking of the endocyclic C–S bond