Kiliani on ketoses: branched carbohydrate building blocks from d-fructose and l-sorbose

Protected branched sugar lactones are available via Kiliani-acetonation sequences on readily available ketoses such as d-fructose and l-sorbose. In both cases, the readily crystallized diacetonides have a 2,3-cis-diol relationship in the product lactone. An efficient double inversion of the configuration at C-4 and C-5 of the product from d-fructose gives access to the formal Kiliani product from l-psicose. Branched carbohydrate lactones are likely to be of significant value as chirons for homochiral targets with functionalized quaternary centres.