Direct conversion of 5,6-unsaturated hexopyranosyl compounds to functionalized cyclohexanones

Hexopyranoid glycosides and glycosyl esters that have an exocyclic double b ond at C-5 (with or without an O-linked substituent at C-6) can be converte d directly, efficiently and under mild conditions to cyclohexanone derivati ves of the inosose or deoxyinosose categories. Usually mercury(II) salts ar e used to promote the process, but Pd(II) compounds can also be employed. C arbon-6 of the starting materials bonds to C-I of aldehydic metal-containin g intermediates, the initial anomeric centres become secondary alcohols, an d the aglycone of the starting materials are lost during the reaction. The C-5 centre becomes a carbonyl group. Otherwise, titanium, aluminium or Grig nard compounds can be used to promote the conversions but, very significant ly, in these instances the products retain the C-I substituents of the star ting materials. Also, when triisobutylaluminium is used, the products isola ted are the alcohols derived by reduction of the carbonyl groups of the ini tially formed cyclohexanones. The reactions have been used in the synthesis of a wide range of inositols, their derivatives, and other compounds conta ining functionalized cyclohexane rings.