This book describes two different projects associated with the chemical (de novo) synthesis of rare and unnatural carbohydrates from readily available starting materials. After a comprehensive introduction to indium chemistry and stereoselective aldol reactions, two new methodologies are presented which complement the synthetic arsenal available to the carbohydrate chemist. The indium mediated allylation of unprotected carbohydrates was applied in the synthesis of acetamido-heptoses and octoses which are constituents of the aminoglycoside antibiotics Apramycin and Destomycin. Furthermore, a new approach for the incorporation of fluorine into carbohydrates is described. Amino acid building blocks were chain-elongated via a titanium mediated aldol addition, finally furnishing amino-, fluoro-functionalised pentoses and hexoses. These compounds are of high interest not only concerning their potential antimicrobial activity but also their usefulness in elucidating fundamental biological processes such as antigen-antibody aggregation.