Chloromethanesulfonate as an efficient leaving group: Rearrangement of thecarbon-carbon bond and conversion of alcohols into azides and nitriles

The chloromethanesulfonate (monochlate) served as an efficient leaving grou p for rearrangement of the carbon-carbon bond and conversion of alcohols in to azides and nitriles. The treatment of the monochlate 16a with zinc aceta te in dioxane at 90 degrees C effected migration of the 4 alpha-methyl grou p to give alkene 17a. Upon similar treatment of the monochlates 22a, 25a, 2 8a, and 31a with zinc acetate, the carbon-carbon bonds antiperiplanar to th e hydroxyl groups efficiently migrated to afford the alkenes 23a, 26a-c, 29 a,b, and 32a, respectively. In the case of the diol 40, the monochlate was converted into the ketone 41 via a rearrangement-ring expansion. The reacti on of the monochlates 44a, 47a, 49a, 52a, and 57a with sodium azide or lith ium azide in N,N-dimethylformamide efficiently afforded the azides with inv ersion of the configuration. The introduction of a nitrile group to the ste rically hindered alcohol 59 was performed in high yield by the reaction of the monochlate 60a with sodium cyanide.