Transformation of Alcohols ; Development of Substitution of Hydroxyl Groups

Alcohols are the most abundant chemicals and should be useful for chemical industry. However, low leaving ability of OH groups retards the development of chemistry based on alcohols. In this research, catalytic subsutition of alcohols was accomplished using indium-silicon combined system. The key species in the catalyst supplies Lewis acid center on silicon in situ. The alkylation reagens have wide application with allylsilane, alkynylsilane, or prennylsilanes. This system showed high chemoselectivity; ester, halo, nitro groups were intert to the reaction system. The used solvent can be hexane that is not halogenated on e although the reported examples by others should use halogenated solvents for catalytic alcohol substitution. This fact strongly contributes to the industrial chemistry based on environmental aspects. The reaction mechanism includes cationic species as a ke y intermediate because tertiary alcohols showed higher reactivity than other alcohols in the reaction system. Therefore, selective alkylation for the compounds bearing primary and tertiary OH groups was well accomplished to give the desired product. This system was also applied to the sugar chemistry. The catalytic substitution of sugar-derivatives by allylsilane in a catalytic manner gave a resource natural product in one-step without any protecting procedures. Even the substrate alcohol has ferrocenic moiety (organometallic part), the reaction proceeded effectively without any effect on the metallo sites. The results described above shows the practical and industrial application for preparation of basic chemicals starting from alcohols. The process will be t he ideal and promising in a future.